Classification Term: 169993

Alliin

C6H11NO3S (177.0459616)

Alliin /ˈæli.ɪn/ is a sulfoxide that is a natural constituent of fresh garlic.[1] It is a derivative of the amino acid cysteine. When fresh garlic is chopped or crushed, the enzyme alliinase converts alliin into allicin, which is responsible for the aroma of fresh garlic. Allicin and other thiosulfinates in garlic are unstable and form a number of other compounds, such as diallyl sulfide (DAS), diallyl disulfide (DADS) and diallyl trisulfide (DAT), dithiins and ajoene.[2] Garlic powder is not a source of alliin, nor is fresh garlic upon maceration, since the enzymatic conversion to allicin takes place in the order of seconds. Alliin was the first natural product found to have both carbon- and sulfur-centered stereochemistry.[3] Constituent of garlic oil (Allium sativum), also from ramsons (Allium ursinum). (R)C(S)S-Alliin is found in garden onion, garlic, and onion-family vegetables. (R)C(S)S-Alliin is found in garden onion. (R)C(S)S-Alliin is a constituent of garlic oil (Allium sativum), also from ramsons (Allium ursinum). Alliin. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=556-27-4 (retrieved 2024-07-01) (CAS RN: 556-27-4). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). Alliin, an orally active sulfoxide compound derived from garlic, exhibits hypoglycemic, antioxidant and anti-inflammatory activities[1][2]. Alliin, an orally active sulfoxide compound derived from garlic, exhibits hypoglycemic, antioxidant and anti-inflammatory activities[1][2].

Cis-Hydroxyproline

C5H9NO3 (131.0582404)

Cis 4-hydroxyproline, also known as L-allo-hydroxyproline or (2s,4s)-4-hydroxy-2-pyrrolidinecarboxylic acid, belongs to proline and derivatives class of compounds. Those are compounds containing proline or a derivative thereof resulting from reaction of proline at the amino group or the carboxy group, or from the replacement of any hydrogen of glycine by a heteroatom. Cis 4-hydroxyproline is soluble (in water) and a moderately acidic compound (based on its pKa). Cis 4-hydroxyproline can be found in a number of food items such as green bell pepper, wheat, nanking cherry, and oat, which makes cis 4-hydroxyproline a potential biomarker for the consumption of these food products. Cis-4-hydroxy-L-proline is l-Proline in which a hydrogen at the 4-position of the pyrrolidine ring is substituted by a hydroxy group (S-configuration). It has a role as a metabolite. It is a non-proteinogenic L-alpha-amino acid and a 4-hydroxyproline. It is a tautomer of a cis-4-hydroxy-L-proline zwitterion. A hydroxylated form of the imino acid proline. A deficiency in ASCORBIC ACID can result in impaired hydroxyproline formation. cis-4-Hydroxyproline is classified as a proline derivative. It is considered to be a soluble (in water), acidic compound. cis-4-Hydroxyproline can be found in numerous foods such as dills, green zucchinis, saskatoon berries, and Japanese pumpkins. L-Proline in which a hydrogen at the 4-position of the pyrrolidine ring is substituted by a hydroxy group (S-configuration). [Spectral] 4-Hydroxy-L-proline (exact mass = 131.05824) and L-Threonine (exact mass = 119.05824) and Taurine (exact mass = 125.01466) were not completely separated on HPLC under the present analytical conditions as described in AC$XXX. Additionally some of the peaks in this data contains dimers and other unidentified ions. KEIO_ID H004 cis-4-Hydroxy-L-proline, a proline analogue, is an inhibitor of collagen production. cis-4-Hydroxy-L-proline could inhibit fibroblast growth by preventing the deposition of triple-helical collagen on the cell layer. cis-4-Hydroxy-L-proline also depresses the growth of primary N-nitrosomethylurea-induced rat mammary tumors[1][2][3][4]. cis-4-Hydroxy-L-proline, a proline analogue, is an inhibitor of collagen production. cis-4-Hydroxy-L-proline could inhibit fibroblast growth by preventing the deposition of triple-helical collagen on the cell layer. cis-4-Hydroxy-L-proline also depresses the growth of primary N-nitrosomethylurea-induced rat mammary tumors[1][2][3][4]. L-Hydroxyproline, one of the hydroxyproline (Hyp) isomers, is a useful chiral building block in the production of many pharmaceuticals. L-Hydroxyproline, one of the hydroxyproline (Hyp) isomers, is a useful chiral building block in the production of many pharmaceuticals.

4-Acetamidobutanoate

C6H11NO3 (145.0738896)

4-Acetamidobutanoic acid, also known as 4-acetamidobutanoate or N-acetyl-4-aminobutyric acid, is a member of the class of compounds known as gamma amino acids and derivatives. These compounds are amino acids having an -NH2 group attached to the gamma carbon atom. 4-Acetamidobutanoic acid is soluble in water. 4-Acetamidobutanoic acid can be found in a number of food items such as Rubus species (blackberry, raspberry), cassava, pepper (Capsicum frutescens), and napa cabbage, which makes 4-acetamidobutanoic acid a potential biomarker for the consumption of these food products. 4-Acetamidobutanoic acid can be found in blood, feces, and urine, as well as in human prostate tissue. 4-Acetamidobutanoic acid exists in all eukaryotes, ranging from yeast to humans. 4-Acetamidobutanoic acid is a GABA derivative, a product of the urea cycle and the metabolism of amino groups, and the product of NAD-linked aldehyde dehydrogenase (EC 1.2.1.3) (KEGG). 4-Acetamidobutanoic acid is a GABA derivative, product of the Urea cycle and metabolism of amino groups, the product of NAD-linked aldehyde dehydrogenase (EC 1.2.1.3) (KEGG) [HMDB]. 4-Acetamidobutanoic acid is found in many foods, some of which are custard apple, japanese walnut, shiitake, and oxheart cabbage. 4-Acetamidobutanoic acid (N-acetyl GABA), the main metabolite of GABA, exhibits antioxidant and antibacterial activities[1]. 4-Acetamidobutanoic acid (N-acetyl GABA), the main metabolite of GABA, exhibits antioxidant and antibacterial activities[1]. 4-Acetamidobutanoic acid (N-acetyl GABA), the main metabolite of GABA, exhibits antioxidant and antibacterial activities[1].

Cysteinylglycine

C5H10N2O3S (178.041211)

Cysteinylglycine is a naturally occurring dipeptide. It is derived from the breakdown of glutathione (a tripeptide). In plasma, cysteinylglycine is in a reduced, oxidized and protein-bound form (aminothiol) and interact via redox and disulphide exchange reactions, in a dynamic system referred to as redox thiol status. (PMID 8642471) Spermatozoa of sub fertile men contain significantly higher thiol concentrations as compared with those of fertile men. The detrimental effect on embryo quality of a high homocysteine (Hcy, another member of the thiol group) concentration in the ejaculate and in follicular fluid is intriguing and may suggest that Hcy is inversely associated with fertility outcome. (PMID 16556671) Rheumatoid arthritis (RA) is a chronic inflammatory disease which involves the synovial membrane of multiple diarthroidal joints causing damage to cartilage and bones. The damage process seems to be related to an overproduction of oxygen reactive species inducing an oxidative perturbation with an increase in some oxidized forms (disulfides and protein mixed disulfides) and a decrease in free thiols. (PMID 15895891) Imipenem (thienamycin formamidine), is a broad-spectrum beta-lactam antibiotic, always used in combination with cilastatin in order to avoid the premature breakdown of imipenem by renal tubular dipeptidase. As this dipeptidase also hydrolyzes the glutathione metabolite cysteinylglycine, the therapeutic association of imipenem and cilastatin causes plasma levels of cysteinylglycine to increase significantly, while cysteine levels are decreased and homocysteine levels are unaffected. Therefore, antibiotic treatment using imipenem-cilastatin induces important metabolic changes that should not remain unrecognized. (PMID 15843241) [HMDB]. Cysteinylglycine is found in many foods, some of which are chinese cabbage, wax apple, garden tomato (variety), and japanese pumpkin. Cysteinylglycine is a naturally occurring dipeptide composed of cysteine and glycine. It is derived from the breakdown of glutathione (a tripeptide). In plasma, cysteinylglycine is in a reduced, oxidized, and protein-bound form (aminothiol) and interacts via redox and disulphide exchange reactions in a dynamic system referred to as redox thiol status (PMID: 8642471). Spermatozoa of sub-fertile men contain significantly higher thiol concentrations as compared with those of fertile men. The detrimental effect on embryo quality of a high homocysteine (Hcy) concentration in the ejaculate and in the follicular fluid is intriguing and may suggest that Hcy is inversely associated with fertility outcome (PMID: 16556671). Rheumatoid arthritis (RA) is a chronic inflammatory disease which involves the synovial membrane of multiple diarthroidal joints causing damage to cartilage and bones. The damage process seems to be related to an overproduction of oxygen reactive species inducing an oxidative perturbation with an increase in some oxidized forms (disulfides and protein mixed disulfides) and a decrease in free thiols (PMID: 15895891). Imipenem (thienamycin formamidine) is a broad-spectrum beta-lactam antibiotic, always used in combination with cilastatin in order to avoid the premature breakdown of imipenem by renal tubular dipeptidase. As this dipeptidase also hydrolyzes the glutathione metabolite cysteinylglycine, the therapeutic association of imipenem and cilastatin causes plasma levels of cysteinylglycine to increase significantly, while cysteine levels are decreased and homocysteine levels are unaffected. Therefore, antibiotic treatment using imipenem-cilastatin induces important metabolic changes that should not remain unrecognized (PMID: 15843241). L-Cysteinylglycine. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=19246-18-5 (retrieved 2024-07-02) (CAS RN: 19246-18-5). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0).

L-Glutamine

C5H10N2O3 (146.069139)

Glutamine (Gln), also known as L-glutamine is an alpha-amino acid. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon). Amino acids are organic compounds that contain amino (–NH2) and carboxyl (–COOH) functional groups, along with a side chain (R group) specific to each amino acid. Structurally, glutamine is similar to the amino acid glutamic acid. However, instead of having a terminal carboxylic acid, it has an amide. Glutamine is one of 20 proteinogenic amino acids, i.e., the amino acids used in the biosynthesis of proteins. Glutamine is found in all organisms ranging from bacteria to plants to animals. It is classified as an aliphatic, polar amino acid. In humans glutamine is considered a non-essential amino acid. Enzymatically, glutamine is formed by replacing a side-chain hydroxyl of glutamic acid with an amine functional group. More specifically, glutamine is synthesized by the enzyme glutamine synthetase from glutamate and ammonia. The most relevant glutamine-producing tissue are skeletal muscles, accounting for about 90\\\\\\% of all glutamine synthesized. Glutamine is also released, in small amounts, by the lungs and brain. In human blood, glutamine is the most abundant free amino acid. Dietary sources of glutamine include protein-rich foods such as beef, chicken, fish, dairy products, eggs, beans, beets, cabbage, spinach, carrots, parsley, vegetable juices, wheat, papaya, Brussels sprouts, celery and kale. Glutamine is one of the few amino acids that can directly cross the blood–brain barrier. Glutamine is often used as a supplement in weightlifting, bodybuilding, endurance and other sports, as well as by those who suffer from muscular cramps or pain, particularly elderly people. In 2017, the U.S. Food and Drug Administration (FDA) approved L-glutamine oral powder, marketed as Endari, to reduce severe complications of sickle cell disease in people aged five years and older with the disorder. Subjects who were treated with L-glutamine oral powder experienced fewer hospital visits for pain treated with a parenterally administered narcotic or ketorolac. The main use of glutamine within the diet of either group is as a means of replenishing the bodys stores of amino acids that have been used during exercise or everyday activities. Studies which have looked into problems with excessive consumption of glutamine thus far have proved inconclusive. However, normal supplementation is healthy mainly because glutamine is supposed to be supplemented after prolonged periods of exercise (for example, a workout or exercise in which amino acids are required for use) and replenishes amino acid stores. This is one of the main reasons glutamine is recommended during fasting or for people who suffer from physical trauma, immune deficiencies, or cancer. There is a significant body of evidence that links glutamine-enriched diets with positive intestinal effects. These include maintenance of gut barrier function, aiding intestinal cell proliferation and differentiation, as well as generally reducing septic morbidity and the symptoms of Irritable Bowel Syndrome (IBS). The reason for such "cleansing" properties is thought to stem from the fact that the intestinal extraction rate of glutamine is higher than that for other amino acids, and is therefore thought to be the most viable option when attempting to alleviate conditions relating to the gastrointestinal tract. These conditions were discovered after comparing plasma concentration within the gut between glutamine-enriched and non glutamine-enriched diets. However, even though glutamine is thought to have "cleansing" properties and effects, it is unknown to what extent glutamine has clinical benefits, due to the varied concentrations of glutamine in varieties of food. It is also known that glutamine has positive effects in reducing healing time after operations. Hospital waiting times after abdominal s... L-glutamine, also known as L-2-aminoglutaramic acid or levoglutamide, is a member of the class of compounds known as L-alpha-amino acids. L-alpha-amino acids are alpha amino acids which have the L-configuration of the alpha-carbon atom. L-glutamine is soluble (in water) and a moderately acidic compound (based on its pKa). L-glutamine can be found in a number of food items such as acorn, yautia, ohelo berry, and oregon yampah, which makes L-glutamine a potential biomarker for the consumption of these food products. L-glutamine can be found primarily in most biofluids, including blood, sweat, breast milk, and cerebrospinal fluid (CSF), as well as throughout most human tissues. L-glutamine exists in all living species, ranging from bacteria to humans. In humans, L-glutamine is involved in several metabolic pathways, some of which include amino sugar metabolism, the oncogenic action of 2-hydroxyglutarate, mercaptopurine metabolism pathway, and transcription/Translation. L-glutamine is also involved in several metabolic disorders, some of which include the oncogenic action of d-2-hydroxyglutarate in hydroxygluaricaciduria, tay-sachs disease, xanthinuria type I, and adenosine deaminase deficiency. Moreover, L-glutamine is found to be associated with carbamoyl Phosphate Synthetase Deficiency, epilepsy, schizophrenia, and alzheimers disease. L-glutamine is a non-carcinogenic (not listed by IARC) potentially toxic compound. L-glutamine is a drug which is used for nutritional supplementation, also for treating dietary shortage or imbalance. L-Glutamine (L-Glutamic acid 5-amide) is a non-essential amino acid present abundantly throughout the body and involved in many metabolic processes. L-Glutamine provides a source of carbons for oxidation in some cells[1][2]. L-Glutamine (L-Glutamic acid 5-amide) is a non-essential amino acid present abundantly throughout the body and involved in many metabolic processes. L-Glutamine provides a source of carbons for oxidation in some cells[1][2]. L-Glutamine (L-Glutamic acid 5-amide) is a non-essential amino acid present abundantly throughout the body and involved in many metabolic processes. L-Glutamine provides a source of carbons for oxidation in some cells[1][2].

Guanidinoacetate

C3H7N3O2 (117.0538242)

Guanidoacetic acid (GAA), also known as guanidinoacetate or glycocyamine, belongs to the class of organic compounds known as alpha amino acids and derivatives. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon), or a derivative thereof. Guanidinoacetic acid was first prepared in 1861 by Adolph Strecker by reaction of cyanamide with glycine in aqueous solution. Manufactured guanidinoacetic acid is primarily used a feed additive approved by EFSA in poultry farming (for fattening), and pigs for fattening. Guanidoacetic acid exists naturally in all vertebrates. It is formed primarily in the kidneys by transferring the guanidine group of L-arginine to the amino acid glycine via the enzyme known as L-Arg:Gly-amidinotransferase (AGAT). In a further step, guanidinoacetate is methylated to generate creatine using S-adenosyl methionine (as the methyl donor) via the enzyme known as guanidinoacetate N-methyltransferase (GAMT). The resulting creatine is released into the bloodstream. Elevated levels of guanidoacetic acid are a characteristic of an inborn metabolic disorder known as Guanidinoacetate Methyltransferase (GAMT) Deficiency. GAMT converts guanidinoacetate to creatine and deficiency of this enzyme results in creatine depletion and accumulation of guanidinoacetate The disorder is transmitted in an autosomal recessive fashion and is localized to mutations on chromosome 19p13.3. GAMT deficiency is characterized by developmental arrest, medication-resistant epilepsy (myoclonic, generalized tonic-clonic, partial complex, atonic), severe speech impairment, progressive dystonia, dyskinesias, hypotonia, ataxia, and autistic-like behavior. Guanidino acetic acid, also known as guanidinoacetate or glycocyamine, belongs to alpha amino acids and derivatives class of compounds. Those are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon), or a derivative thereof. Guanidino acetic acid is slightly soluble (in water) and a weakly acidic compound (based on its pKa). Guanidino acetic acid can be found in apple and loquat, which makes guanidino acetic acid a potential biomarker for the consumption of these food products. Guanidino acetic acid can be found primarily in most biofluids, including cellular cytoplasm, feces, urine, and cerebrospinal fluid (CSF), as well as in human brain, kidney and liver tissues. In humans, guanidino acetic acid is involved in a couple of metabolic pathways, which include arginine and proline metabolism and glycine and serine metabolism. Guanidino acetic acid is also involved in several metabolic disorders, some of which include dihydropyrimidine dehydrogenase deficiency (DHPD), hyperprolinemia type II, prolinemia type II, and hyperornithinemia-hyperammonemia-homocitrullinuria [hhh-syndrome]. Moreover, guanidino acetic acid is found to be associated with chronic renal failure and schizophrenia. Guanidino acetic acid is a non-carcinogenic (not listed by IARC) potentially toxic compound. Chronic Exposure: Kidney dialysis is usually needed to relieve the symptoms of uremic syndrome until normal kidney function can be restored. D019995 - Laboratory Chemicals > D007202 - Indicators and Reagents > D000345 - Affinity Labels Acquisition and generation of the data is financially supported in part by CREST/JST.

1-methyl-4-imidazoleacetate

C6H8N2O2 (140.0585748)

Methylimidazoleacetic acid is the main metabolite of histamine. This end product of histamine catabolism is formed by N-methylation in the imidazole ring to methylhistamine by histamine methyltransferase (EC 2.1.1.8) and a subsequent oxidative deamination in the side chain by type B monoamine oxidase (EC 1.4.3.4). Based on studies, it is known that as much as 70 to 80 percent of the histamine metabolized in the body is excreted in the urine as methylimidazoleacetic acid. Thus, urinary methylimidazoleacetic acid being the major and specific histamine metabolite is a clear marker of any changes in histamine metabolism in the body. The urinary excretion of methylimidazoleacetic acid is considered a reliable indicator of histamine turnover rate in the body. The excretion of methylimidazoleacetic acid is higher in men than in women. However, this gender difference is abolished when corrected for creatinine excretion. A possible explanation is that basal histamine turnover is related to body size. There is no significant difference in methylimidazoleacetic acid excretion between smokers and non-smokers when analyzing absolute values (mg/24 h). When using methylimidazoleacetic acid values corrected for creatinine excretion female smokers have significantly higher methylimidazoleacetic acid excretion compared to nonsmokers (PMID:11411609, 7130180, 10350179, 10202992). Methylimidazoleacetic acid is the main metabolite of histamine. This end product of histamine catabolism is formed by N-methylation in the imidazole ring to methylhistamine by histamine methyltransferase (EC 2.1.1.8) and a subsequent oxidative deamination in the side chain by type B monoamine oxidase (EC 1.4.3.4). From studies is known that as much as 70 to 80 percent of the histamine metabolized in the body is excreted in the urine as Methylimidazoleacetic acid. Thus, urinary Methylimidazoleacetic acid being the major and specific histamine metabolite is a clear marker of any changes in histamine metabolism in the body. The urinary excretion of methylimidazoleacetic acid is considered a reliable indicator of histamine turnover rate in the body. The excretion of Methylimidazoleacetic acid is higher in men than women however; this gender difference is abolished when corrected for creatinine excretion. A possible explanation is that basal histamine turnover is related to body size. There is no significant difference in Methylimidazoleacetic acid excretion between smokers and non-smokers when analysing absolute values (mg/24 h). When using Methylimidazoleacetic acid values corrected for creatinine excretion female smokers have significantly higher Methylimidazoleacetic acid excretion compared to nonsmokers. (PMID: 11411609, 7130180, 10350179, 10202992) [HMDB]

N-acetylglutamate

C7H11NO5 (189.0637196)

N-Acetyl-L-glutamic acid or N-Acetylglutamate, belongs to the class of organic compounds known as N-acyl-alpha amino acids. N-acyl-alpha amino acids are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. N-Acetyl-L-glutamate can also be classified as an alpha amino acid or a derivatized alpha amino acid. Technically, N-Acetyl-L-glutamate is a biologically available N-terminal capped form of the proteinogenic alpha amino acid L-glutamic acid. N-Acetyl-L-glutamic acid is found in all organisms ranging from bacteria to plants to animals. N-acetyl amino acids can be produced either via direct synthesis of specific N-acetyltransferases or via the proteolytic degradation of N-acetylated proteins by specific hydrolases. N-terminal acetylation of proteins is a widespread and highly conserved process in eukaryotes that is involved in protection and stability of proteins (PMID: 16465618). About 85\\\\% of all human proteins and 68\\\\% of all yeast proteins are acetylated at their N-terminus (PMID: 21750686). Several proteins from prokaryotes and archaea are also modified by N-terminal acetylation. The majority of eukaryotic N-terminal-acetylation reactions occur through N-acetyltransferase enzymes or NAT’s (PMID: 30054468). These enzymes consist of three main oligomeric complexes NatA, NatB, and NatC, which are composed of at least a unique catalytic subunit and one unique ribosomal anchor. The substrate specificities of different NAT enzymes are mainly determined by the identities of the first two N-terminal residues of the target protein. The human NatA complex co-translationally acetylates N-termini that bear a small amino acid (A, S, T, C, and occasionally V and G) (PMID: 30054468). NatA also exists in a monomeric state and can post-translationally acetylate acidic N-termini residues (D-, E-). NatB and NatC acetylate N-terminal methionine with further specificity determined by the identity of the second amino acid. N-acetylated amino acids, such as N-acetylglutamate can be released by an N-acylpeptide hydrolase from peptides generated by proteolytic degradation (PMID: 16465618). In addition to the NAT enzymes and protein-based acetylation, N-acetylation of free glutamic acid can also occur. In particular, N-Acetyl-L-glutamic acid can be biosynthesized from glutamate and acetylornithine by ornithine acetyltransferase, and from glutamic acid and acetyl-CoA by the enzyme known as N-acetylglutamate synthase. N-Acetyl-L-glutamic acid is the first intermediate involved in the biosynthesis of arginine in prokaryotes and simple eukaryotes and a regulator of the urea cycle in vertebrates. In vertebrates, N-acetylglutamic acid is the allosteric activator molecule to mitochondrial carbamyl phosphate synthetase I (CPSI) which is the first enzyme in the urea cycle. It triggers the production of the first urea cycle intermediate, a compound known as carbamyl phosphate. Notably the CPSI enzyme is inactive when N-acetylglutamic acid is not present. A deficiency in N-acetyl glutamate synthase or a genetic mutation in the gene coding for the enzyme will lead to urea cycle failure in which ammonia is not converted to urea, but rather accumulated in the blood leading to the condition called Type I hyperammonemia. Excessive amounts N-acetyl amino acids can be detected in the urine with individuals with aminoacylase I deficiency, a genetic disorder (PMID: 16465618). These include N-acetylalanine (as well as N-acetylserine, N-acetylglutamine, N-acetylglutamate, N-acetylglycine, N-acetylmethionine and smaller amounts of N-acetylthreonine, N-acetylleucine, N-acetylvaline and N-acetylisoleucine. Aminoacylase I is a soluble homodimeric zinc binding enzyme that catalyzes the formation of free aliphatic amino acids from N-acetylated precursors. In humans, Aminoacylase I is encoded by the aminoacylase 1 gene (ACY1) on chromosome 3p21 that consists of 15 exons (OMIM 609924). Individuals with aminoacylase I deficiency w... N-acetyl-l-glutamate, also known as L-N-acetylglutamic acid or ac-glu-oh, belongs to glutamic acid and derivatives class of compounds. Those are compounds containing glutamic acid or a derivative thereof resulting from reaction of glutamic acid at the amino group or the carboxy group, or from the replacement of any hydrogen of glycine by a heteroatom. N-acetyl-l-glutamate is soluble (in water) and a weakly acidic compound (based on its pKa). N-acetyl-l-glutamate can be found in a number of food items such as cardoon, almond, butternut squash, and avocado, which makes N-acetyl-l-glutamate a potential biomarker for the consumption of these food products. N-acetyl-l-glutamate may be a unique S.cerevisiae (yeast) metabolite. Acquisition and generation of the data is financially supported in part by CREST/JST. KEIO_ID A031 N-Acetyl-L-glutamic acid, a glutamic acid, is a component of animal cell culturing media. N-Acetyl-L-glutamic acid is a metabolite of Saccharomyces cerevisiae and human[1]. N-Acetyl-L-glutamic acid, a glutamic acid, is a component of animal cell culturing media. N-Acetyl-L-glutamic acid is a metabolite of Saccharomyces cerevisiae and human[1].

S-adenosylhomocysteine (SAH)

C14H20N6O5S (384.12158300000004)

S-Adenosyl-L-homocysteine (SAH) is formed by the demethylation of S-adenosyl-L-methionine. S-Adenosylhomocysteine (AdoHcy or SAH) is also the immediate precursor of all of the homocysteine produced in the body. The reaction is catalyzed by S-adenosylhomocysteine hydrolase and is reversible with the equilibrium favoring formation of SAH. In vivo, the reaction is driven in the direction of homocysteine formation by the action of the enzyme adenosine deaminase which converts the second product of the S-adenosylhomocysteine hydrolase reaction, adenosine, to inosine. Except for methyl transfer from betaine and from methylcobalamin in the methionine synthase reaction, SAH is the product of all methylation reactions that involve S-adenosylmethionine (SAM) as the methyl donor. Methylation is significant in epigenetic regulation of protein expression via DNA and histone methylation. The inhibition of these SAM-mediated processes by SAH is a proven mechanism for metabolic alteration. Because the conversion of SAH to homocysteine is reversible, with the equilibrium favoring the formation of SAH, increases in plasma homocysteine are accompanied by an elevation of SAH in most cases. Disturbances in the transmethylation pathway indicated by abnormal SAH, SAM, or their ratio have been reported in many neurodegenerative diseases, such as dementia, depression, and Parkinsons disease (PMID:18065573, 17892439). Therefore, when present in sufficiently high levels, S-adenosylhomocysteine can act as an immunotoxin and a metabotoxin. An immunotoxin disrupts, limits the function, or destroys immune cells. A metabotoxin is an endogenous metabolite that causes adverse health effects at chronically high levels. Chronically high levels of S-adenosylhomocysteine are associated with S-adenosylhomocysteine (SAH) hydrolase deficiency and adenosine deaminase deficiency. S-Adenosylhomocysteine forms when there are elevated levels of homocysteine and adenosine. S-Adenosyl-L-homocysteine is a potent inhibitor of S-adenosyl-L-methionine-dependent methylation reactions. It is toxic to immature lymphocytes and can lead to immunosuppression (PMID:221926). S-adenosylhomocysteine, also known as adohcy or sah, is a member of the class of compounds known as 5-deoxy-5-thionucleosides. 5-deoxy-5-thionucleosides are 5-deoxyribonucleosides in which the ribose is thio-substituted at the 5position by a S-alkyl group. S-adenosylhomocysteine is slightly soluble (in water) and a moderately acidic compound (based on its pKa). S-adenosylhomocysteine can be found in a number of food items such as rapini, european plum, rambutan, and pepper (c. pubescens), which makes S-adenosylhomocysteine a potential biomarker for the consumption of these food products. S-adenosylhomocysteine can be found primarily in blood, cerebrospinal fluid (CSF), feces, and urine, as well as throughout most human tissues. S-adenosylhomocysteine exists in all living species, ranging from bacteria to humans. In humans, S-adenosylhomocysteine is involved in several metabolic pathways, some of which include phosphatidylcholine biosynthesis PC(14:0/18:3(9Z,12Z,15Z)), phosphatidylcholine biosynthesis PC(22:4(7Z,10Z,13Z,16Z)/22:0), phosphatidylcholine biosynthesis PC(20:3(5Z,8Z,11Z)/22:2(13Z,16Z)), and phosphatidylcholine biosynthesis PC(18:3(6Z,9Z,12Z)/22:5(7Z,10Z,13Z,16Z,19Z)). S-adenosylhomocysteine is also involved in several metabolic disorders, some of which include 3-phosphoglycerate dehydrogenase deficiency, hawkinsinuria, non ketotic hyperglycinemia, and tyrosine hydroxylase deficiency. Moreover, S-adenosylhomocysteine is found to be associated with neurodegenerative disease and parkinsons disease. S-adenosylhomocysteine is a non-carcinogenic (not listed by IARC) potentially toxic compound. S-Adenosyl-L-homocysteine (SAH) is an amino acid derivative used in several metabolic pathways in most organisms. It is an intermediate in the synthesis of cysteine and adenosine . [Spectral] S-Adenosyl-L-homocysteine (exact mass = 384.12159) and Adenosine (exact mass = 267.09675) were not completely separated on HPLC under the present analytical conditions as described in AC$XXX. Additionally some of the peaks in this data contains dimers and other unidentified ions. [Spectral] S-Adenosyl-L-homocysteine (exact mass = 384.12159) and Cytidine (exact mass = 243.08552) were not completely separated on HPLC under the present analytical conditions as described in AC$XXX. Additionally some of the peaks in this data contains dimers and other unidentified ions. Acquisition and generation of the data is financially supported in part by CREST/JST. COVID info from PDB, Protein Data Bank, WikiPathways Corona-virus Coronavirus SARS-CoV-2 COVID-19 SARS-CoV COVID19 SARS2 SARS SAH (S-Adenosylhomocysteine) is an amino acid derivative and a modulartor in several metabolic pathways. It is an intermediate in the synthesis of cysteine and adenosine[1]. SAH is an inhibitor for METTL3-METTL14 heterodimer complex (METTL3-14) with an IC50 of 0.9 μM[2]. SAH (S-Adenosylhomocysteine) is an amino acid derivative and a modulartor in several metabolic pathways. It is an intermediate in the synthesis of cysteine and adenosine[1]. SAH is an inhibitor for METTL3-METTL14 heterodimer complex (METTL3-14) with an IC50 of 0.9 μM[2].

N-acetylaspartate (NAA)

C6H9NO5 (175.0480704)

N-Acetyl-L-Aspartic acid (NAA) or N-Acetylaspartic acid, belongs to the class of organic compounds known as N-acyl-alpha amino acids. N-acyl-alpha amino acids are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. N-alpha-Acetyl-L-aspartic acid can also be classified as an alpha amino acid or a derivatized alpha amino acid. Technically, N-Acetyl-L-aspartic acid is a biologically available N-terminal capped form of the proteinogenic alpha amino acid L-aspartic acid. N-acetyl amino acids can be produced either via direct synthesis of specific N-acetyltransferases or via the proteolytic degradation of N-acetylated proteins by specific hydrolases. N-terminal acetylation of proteins is a widespread and highly conserved process in eukaryotes that is involved in protection and stability of proteins (PMID: 16465618). About 85\\\% of all human proteins and 68\\\% of all yeast proteins are acetylated at their N-terminus (PMID: 21750686). Several proteins from prokaryotes and archaea are also modified by N-terminal acetylation. The majority of eukaryotic N-terminal-acetylation reactions occur through N-acetyltransferase enzymes or NAT’s (PMID: 30054468). These enzymes consist of three main oligomeric complexes NatA, NatB, and NatC, which are composed of at least a unique catalytic subunit and one unique ribosomal anchor. The substrate specificities of different NAT enzymes are mainly determined by the identities of the first two N-terminal residues of the target protein. The human NatA complex co-translationally acetylates N-termini that bear a small amino acid (A, S, T, C, and occasionally V and G) (PMID: 30054468). NatA also exists in a monomeric state and can post-translationally acetylate acidic N-termini residues (D-, E-). NatB and NatC acetylate N-terminal methionine with further specificity determined by the identity of the second amino acid. N-acetylated amino acids, such as N-acetylaspartate can be released by an N-acylpeptide hydrolase from peptides generated by proteolytic degradation (PMID: 16465618). In addition to the NAT enzymes and protein-based acetylation, N-acetylation of free aspartic acid can also occur. In particular, N-Acetyl-L-aspartic acid can be synthesized in neurons from the amino acid aspartate and acetyl coenzyme A (acetyl CoA). Specifically, the enzyme known as aspartate N-acetyltransferase (EC 2.3.1.17) catalyzes the transfer of the acetyl group of acetyl CoA to the amino group of aspartate. N-Acetyl-L-aspartic acid is the second most concentrated molecule in the brain after the amino acid glutamate. The various functions served by N-acetylaspartic acid are still under investigation, but the primary proposed functions include (1) acting as a neuronal osmolyte that is involved in fluid balance in the brain, (2) serving as a source of acetate for lipid and myelin synthesis in oligodendrocytes (the glial cells that myelinate neuronal axons), (3) serving as a precursor for the synthesis of the important dipeptide neurotransmitter N-acetylaspartylglutamate (NAAG), and (4) playing a potential role in energy production from the amino acid glutamate in neuronal mitochondria. High neurotransmitter (i.e. N-acetylaspartic acid) levels can lead to abnormal neural signaling, delayed or arrested intellectual development, and difficulties with general motor skills. When present in sufficiently high levels, N-acetylaspartic acid can be a neurotoxin, an acidogen, and a metabotoxin. A neurotoxin is a compound that disrupts or attacks neural tissue. An acidogen is an acidic compound that induces acidosis, which has multiple adverse effects on many organ systems. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of N-acetylaspartic acid are associated with Canavan disease. Because N-acetylaspartic acid functions as an organic acid and high levels of organic acids can lead to a condition known... N-Acetylaspartic acid is a derivative of aspartic acid. It is the second most concentrated molecule in the brain after the amino acid glutamate. It is synthesized in neurons from the amino acid aspartate and acetyl coenzyme A. The various functions served by N-acetylaspartic acid are still under investigation, but the primary proposed functions include: Acquisition and generation of the data is financially supported in part by CREST/JST. D018377 - Neurotransmitter Agents > D018846 - Excitatory Amino Acids KEIO_ID A142 N-Acetyl-L-aspartic acid is a derivative of aspartic acid.

N-acetyl-aspartyl-glutamate (NAAG)

C11H16N2O8 (304.0906616)

N-Acetylaspartylglutamate (NAAG) is a neuropeptide found in millimolar concentrations in the brain that is localized to subpopulations of glutamatergic, cholinergic, GABAergic, and noradrenergic neuronal systems. NAAG is released upon depolarization by a Ca(2+)-dependent process and is an agonist at mGluR3 receptors and an antagonist at NMDA receptors. NAAG is catabolized to N-acetylaspartate and glutamate primarily by glutamate carboxypeptidase II, which is expressed on the extracellular surface of astrocytes. The levels of NAAG and the activity of carboxypeptidase II are altered in a regionally specific fashion in several neuropsychiatric disorders (PMID:9361299). N-Acetylaspartylglutamic acid (NAAG) is a purported precursor of N-acetylaspartic acid (NAA) and is present at about one-tenth of the concentration of NAA in the brain. NAAG has been reported to activate N-methyl-D-aspartic acid (NMDA) receptors in neurons. Previous immunohistochemical studies in the vertebrate central nervous system (CNS) have suggested that NAAG is exclusively localized to neurons. Recent evidence, however, indicates that NAAG might also be localized to nonneuronal cells within the CNS. Only traces of NAA and NAAG are detectable in other tissues. Some compounds can change levels of NAA and NAAG in the brain. For example, methylphenidate increases the levels of NAA and NAAG in the cerebral cortex; amphetamine also increases NAA concentration in a mature brain by 26\\\%, raising the possibility that other neurochemical systems might be involved in the clinical effects of stimulants (PMID:10603234). N-Acetylaspartylglutamate (NAAG) is a neuropeptide found in millimolar concentrations in brain that is localized to subpopulations of glutamatergic, cholinergic, GABAergic, and noradrenergic neuronal systems. NAAG is released upon depolarization by a Ca(2+)-dependent process and is an agonist at mGluR3 receptors and an antagonist at NMDA receptors. NAAG is catabolized to N-acetylaspartate and glutamate primarily by glutamate carboxypeptidase II, which is expressed on the extracellular surface of astrocytes. The levels of NAAG and the activity of carboxypeptidase II are altered in a regionally specific fashion in several neuropsychiatric disorders. (PMID 9361299) D019141 - Respiratory System Agents > D018927 - Anti-Asthmatic Agents > D001993 - Bronchodilator Agents D018377 - Neurotransmitter Agents > D018494 - Histamine Agents > D006633 - Histamine Antagonists D002491 - Central Nervous System Agents > D018696 - Neuroprotective Agents D018373 - Peripheral Nervous System Agents > D001337 - Autonomic Agents D009676 - Noxae > D009498 - Neurotoxins D018926 - Anti-Allergic Agents D020011 - Protective Agents Spaglumic Acid (N-Acetylaspartylglutamic acid) is a neuropeptide found in millimolar concentrations in brain.

Glycine

C2H5NO2 (75.032027)

Glycine (Gly), is an alpha-amino acid. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon). Amino acids are organic compounds that contain amino (–NH2) and carboxyl (–COOH) functional groups, along with a side chain (R group) specific to each amino acid. Glycine is one of 20 proteinogenic amino acids, i.e., the amino acids used in the biosynthesis of proteins. Glycine is found in all organisms ranging from bacteria to plants to animals. It is classified as an aliphatic, non-polar amino acid and is the simplest of all amino acids. In humans, glycine is a nonessential amino acid, although experimental animals show reduced growth on low-glycine diets. The average adult human ingests 3 to 5 grams of glycine daily. Glycine is a colorless, sweet-tasting crystalline solid. It is the only achiral proteinogenic amino acid. Glycine was discovered in 1820 by the French chemist Henri Braconnot when he hydrolyzed gelatin by boiling it with sulfuric acid. The name comes from the Greek word glucus or "sweet tasting". Glycine is biosynthesized in the body from the amino acid serine, which is in turn derived from 3-phosphoglycerate. In the liver of vertebrates, glycine synthesis is catalyzed by glycine synthase (also called glycine cleavage enzyme). In addition to being synthesized from serine, glycine can also be derived from threonine, choline or hydroxyproline via inter-organ metabolism of the liver and kidneys. Glycine is degraded via three pathways. The predominant pathway in animals and plants is the reverse of the glycine synthase pathway. In this context, the enzyme system involved glycine metabolism is called the glycine cleavage system. The glycine cleavage system catalyzes the oxidative conversion of glycine into carbon dioxide and ammonia, with the remaining one-carbon unit transferred to folate as methylenetetrahydrofolate. It is the main catabolic pathway for glycine and it also contributes to one-carbon metabolism. Patients with a deficiency of this enzyme system have increased glycine in plasma, urine, and cerebrospinal fluid (CSF) with an increased CSF:plasma glycine ratio (PMID: 16151895). Glycine levels are effectively measured in plasma in both normal patients and those with inborn errors of glycine metabolism (http://www.dcnutrition.com/AminoAcids/). Nonketotic hyperglycinaemia (OMIM: 606899) is an autosomal recessive condition caused by deficient enzyme activity of the glycine cleavage enzyme system (EC 2.1.1.10). The glycine cleavage enzyme system comprises four proteins: P-, T-, H- and L-proteins (EC 1.4.4.2, EC 2.1.2.10, and EC 1.8.1.4 for P-, T-, and L-proteins). Mutations have been described in the GLDC (OMIM: 238300), AMT (OMIM: 238310), and GCSH (OMIM: 238330) genes encoding the P-, T-, and H-proteins respectively. Glycine is involved in the bodys production of DNA, hemoglobin, and collagen, and in the release of energy. The principal function of glycine is as a precursor to proteins. Most proteins incorporate only small quantities of glycine, a notable exception being collagen, which contains about 35\\\\\\% glycine. In higher eukaryotes, delta-aminolevulinic acid, the key precursor to porphyrins (needed for hemoglobin and cytochromes), is biosynthesized from glycine and succinyl-CoA by the enzyme ALA synthase. Glycine provides the central C2N subunit of all purines, which are key constituents of DNA and RNA. Glycine is an inhibitory neurotransmitter in the central nervous system, especially in the spinal cord, brainstem, and retina. When glycine receptors are activated, chloride enters the neuron via ionotropic receptors, causing an inhibitory postsynaptic potential (IPSP). Glycine. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=56-40-6 (retrieved 2024-07-02) (CAS RN: 56-40-6). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). Glycine is an inhibitory neurotransmitter in the CNS and also acts as a co-agonist along with glutamate, facilitating an excitatory potential at the glutaminergic N-methyl-D-aspartic acid (NMDA) receptors. Glycine is an inhibitory neurotransmitter in the CNS and also acts as a co-agonist along with glutamate, facilitating an excitatory potential at the glutaminergic N-methyl-D-aspartic acid (NMDA) receptors. Glycine is orally active. Glycine can be used to study cell protection, cancer, neurological diseases, and angiogenesis[1][2][3][4][5][6]. Glycine is an inhibitory neurotransmitter in the CNS and also acts as a co-agonist along with glutamate, facilitating an excitatory potential at the glutaminergic N-methyl-D-aspartic acid (NMDA) receptors.

Hypotaurine

C2H7NO2S (109.0197482)

Hypotaurine belongs to the class of organic compounds known as sulfinic acids. Sulfinic acids are compounds containing a sulfinic acid functional group, with the general structure RS(=O)OH (R = organyl, not H). Hypotaurine exists in all living species, ranging from bacteria to humans. Within humans, hypotaurine participates in a number of enzymatic reactions. In particular, hypotaurine can be biosynthesized from cysteamine; which is catalyzed by the enzyme 2-aminoethanethiol dioxygenase. In addition, hypotaurine can be biosynthesized from 3-sulfinoalanine through its interaction with the enzyme cysteine sulfinic acid decarboxylase. In humans, hypotaurine is involved in taurine and hypotaurine metabolism. [Spectral] Hypotaurine (exact mass = 109.01975) and Cytosine (exact mass = 111.04326) were not completely separated on HPLC under the present analytical conditions as described in AC$XXX. Additionally some of the peaks in this data contains dimers and other unidentified ions. Hypotaurine is a product of enzyme cysteamine dioxygenase [EC 1.13.11.19] in taurine and hypotaurine metabolism pathway (KEGG). It may function as an antioxidant and a protective agent under physiological conditions (PMID 14992269). [HMDB] Hypotaurine (2-aminoethanesulfinic acid), an intermediate in taurine biosynthesis from cysteine in astrocytes, is an endogenous inhibitory amino acid of the glycine receptor. Antioxidant[1].

L-Alanine

C3H7NO2 (89.0476762)

Alanine (Ala), also known as L-alanine is an alpha-amino acid. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon). Amino acids are organic compounds that contain amino (–NH2) and carboxyl (–COOH) functional groups, along with a side chain (R group) specific to each amino acid. L-alanine is one of 20 proteinogenic amino acids, i.e., the amino acids used in the biosynthesis of proteins. Alanine is found in all organisms ranging from bacteria to plants to animals. It is classified as an aliphatic, non-polar amino acid. In humans, alanine is a non-essential amino acid that can be easily made in the body from either the conversion of pyruvate or the breakdown of the dipeptides carnosine and anserine. Alanine can be also synthesized from branched chain amino acids such as valine, leucine, and isoleucine. Alanine is produced by reductive amination of pyruvate through a two-step process. In the first step, alpha-ketoglutarate, ammonia and NADH are converted by the enzyme known glutamate dehydrogenase to glutamate, NAD+ and water. In the second step, the amino group of the newly-formed glutamate is transferred to pyruvate by an aminotransferase enzyme, regenerating the alpha-ketoglutarate, and converting the pyruvate to alanine. The net result is that pyruvate and ammonia are converted to alanine. In mammals, alanine plays a key role in glucose–alanine cycle between tissues and liver. In muscle and other tissues that degrade amino acids for fuel, amino groups are collected in the form of glutamate by transamination. Glutamate can then transfer its amino group to pyruvate, a product of muscle glycolysis, through the action of alanine aminotransferase, forming alanine and alpha-ketoglutarate. The alanine enters the bloodstream and is transported to the liver. The alanine aminotransferase reaction takes place in reverse in the liver, where the regenerated pyruvate is used in gluconeogenesis, forming glucose which returns to the muscles through the circulation system. Alanine is highly concentrated in muscle and is one of the most important amino acids released by muscle, functioning as a major energy source. Plasma alanine is often decreased when the BCAA (branched-chain amino acids) are deficient. This finding may relate to muscle metabolism. Alanine is highly concentrated in meat products and other high-protein foods like wheat germ and cottage cheese. Alanine is an important participant as well as a regulator of glucose metabolism. Alanine levels parallel blood sugar levels in both diabetes and hypoglycemia, and alanine is reduced in both severe hypoglycemia and the ketosis of diabetes. Alanine is an important amino acid for lymphocyte reproduction and immunity. Alanine therapy has helped dissolve kidney stones in experimental animals. Normal alanine metabolism, like that of other amino acids, is highly dependent upon enzymes that contain vitamin B6. Alanine, like GABA, taurine, and glycine, is an inhibitory neurotransmitter in the brain (http://www.dcnutrition.com/AminoAcids/). L-Alanine. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=56-41-7 (retrieved 2024-07-01) (CAS RN: 56-41-7). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). L-Alanine is a non-essential amino acid, involved in sugar and acid metabolism, increases immunity, and provides energy for muscle tissue, brain, and central nervous system. L-Alanine is a non-essential amino acid, involved in sugar and acid metabolism, increases immunity, and provides energy for muscle tissue, brain, and central nervous system.

Urea

CH4N2O (60.0323614)

Urea is a highly soluble organic compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids. Urea is formed in a cyclic pathway known simply as the urea cycle. In this cycle, amino groups donated by ammonia and L-aspartate are converted to urea. Urea is essentially a waste product; it has no physiological function. It is dissolved in blood (in humans in a concentration of 2.5 - 7.5 mmol/liter) and excreted by the kidney in the urine. In addition, a small amount of urea is excreted (along with sodium chloride and water) in human sweat. Urea is found to be associated with primary hypomagnesemia, which is an inborn error of metabolism. B - Blood and blood forming organs > B05 - Blood substitutes and perfusion solutions > B05B - I.v. solutions > B05BC - Solutions producing osmotic diuresis Formulation aid. Cattle feed supplement. Urea is found in many foods, some of which are globe artichoke, hickory nut, hard wheat, and cherry tomato. D - Dermatologicals > D02 - Emollients and protectives > D02A - Emollients and protectives > D02AE - Carbamide products C78275 - Agent Affecting Blood or Body Fluid > C448 - Diuretic > C49187 - Osmotic Diuretic Urea is a powerful protein denaturant via both direct and indirect mechanisms[1]. A potent emollient and keratolytic agent[2]. Used as a diuretic agent. Blood urea nitrogen (BUN) has been utilized to evaluate renal function[3]. Widely used in fertilizers as a source of nitrogen and is an important raw material for the chemical industry. Urea is a powerful protein denaturant via both direct and indirect mechanisms[1]. A potent emollient and keratolytic agent[2]. Used as a diuretic agent. Blood urea nitrogen (BUN) has been utilized to evaluate renal function[3]. Widely used in fertilizers as a source of nitrogen and is an important raw material for the chemical industry.

Asymmetric dimethylarginine

C8H18N4O2 (202.1429688)

Asymmetric dimethylarginine (ADMA) is a naturally occurring chemical found in blood plasma. It is a metabolic by-product of continual protein modification processes in the cytoplasm of all human cells. It is closely related to L-arginine, a conditionally-essential amino acid. ADMA interferes with L-arginine in the production of nitric oxide, a key chemical to endothelial and hence cardiovascular health. Asymmetric dimethylarginine is created in protein methylation, a common mechanism of post-translational protein modification. This reaction is catalyzed by an enzyme set called S-adenosylmethionine protein N-methyltransferases (protein methylases I and II). The methyl groups transferred to create ADMA are derived from the methyl group donor S-adenosylmethionine, an intermediate in the metabolism of homocysteine. (Homocysteine is an important blood chemical, because it is also a marker of cardiovascular disease). After synthesis, ADMA migrates into the extracellular space and thence into blood plasma. Asymmetric dimethylarginine is measured using high performance liquid chromatography. ADMA has been identified as a uremic toxin according to the European Uremic Toxin Working Group (PMID: 22626821). Isolated from broad bean seeds (Vicia faba). NG,NG-Dimethyl-L-arginine is found in many foods, some of which are yellow wax bean, spinach, green zucchini, and white cabbage. D004791 - Enzyme Inhibitors Asymmetric dimethylarginine is an endogenous inhibitor of nitric oxide synthase (NOS), and functions as a marker of endothelial dysfunction in a number of pathological states.

N-Acetylhistidine

C8H11N3O3 (197.0800376)

N-Acetyl-L-histidine or N-Acetylhistidine, belongs to the class of organic compounds known as N-acyl-alpha amino acids. N-acyl-alpha amino acids are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. N-Acetylhistidine can also be classified as an alpha amino acid or a derivatized alpha amino acid. Technically, N-Acetylhistidine is a biologically available N-terminal capped form of the proteinogenic alpha amino acid L-histidine. N-acetyl amino acids can be produced either via direct synthesis of specific N-acetyltransferases or via the proteolytic degradation of N-acetylated proteins by specific hydrolases. N-terminal acetylation of proteins is a widespread and highly conserved process in eukaryotes that is involved in protection and stability of proteins (PMID: 16465618). About 85\\% of all human proteins and 68\\% of all yeast proteins are acetylated at their N-terminus (PMID: 21750686). Several proteins from prokaryotes and archaea are also modified by N-terminal acetylation. The majority of eukaryotic N-terminal-acetylation reactions occur through N-acetyltransferase enzymes or NAT’s (PMID: 30054468). These enzymes consist of three main oligomeric complexes NatA, NatB, and NatC, which are composed of at least a unique catalytic subunit and one unique ribosomal anchor. The substrate specificities of different NAT enzymes are mainly determined by the identities of the first two N-terminal residues of the target protein. The human NatA complex co-translationally acetylates N-termini that bear a small amino acid (A, S, T, C, and occasionally V and G) (PMID: 30054468). NatA also exists in a monomeric state and can post-translationally acetylate acidic N-termini residues (D-, E-). NatB and NatC acetylate N-terminal methionine with further specificity determined by the identity of the second amino acid. N-acetylated amino acids, such as N-acetylhistidine can be released by an N-acylpeptide hydrolase from peptides generated by proteolytic degradation (PMID: 16465618). In addition to the NAT enzymes and protein-based acetylation, N-acetylation of free histidine can also occur. In particular, N-Acetylhistidine can be biosynthesized from L-histidine and acetyl-CoA by the enzyme histidine N-acetyltransferase (EC 2.3.1.33). Many N-acetylamino acids are classified as uremic toxins if present in high abundance in the serum or plasma (PMID: 26317986; PMID: 20613759). Uremic toxins are a diverse group of endogenously produced molecules that, if not properly cleared or eliminated by the kidneys, can cause kidney damage, cardiovascular disease and neurological deficits (PMID: 18287557). Constituent of the tissues of various fish and amphibian subspecies N-Acetylhistidine is found in fishes. KEIO_ID A073

γ-Aminobutyric acid

C4H9NO2 (103.0633254)

gamma-Aminobutyric acid (GABA) is an inhibitory neurotransmitter found in the nervous systems of widely divergent species, including humans. It is the chief inhibitory neurotransmitter in the vertebrate central nervous system. In vertebrates, GABA acts at inhibitory synapses in the brain. It acts by binding to specific transmembrane receptors in the plasma membrane of both pre- and postsynaptic neurons. This binding causes the opening of ion channels to allow either the flow of negatively-charged chloride ions into the cell or positively-charged potassium ions out of the cell. This will typically result in a negative change in the transmembrane potential, usually causing hyperpolarization. Three general classes of GABA receptor are known (PMID: 10561820). These include GABA-A and GABA-C ionotropic receptors, which are ion channels themselves, and GABA-B metabotropic receptors, which are G protein-coupled receptors that open ion channels via intermediaries known as G proteins (PMID: 10561820). Activation of the GABA-B receptor by GABA causes neuronal membrane hyperpolarization and a resultant inhibition of neurotransmitter release. In addition to binding sites for GABA, the GABA-A receptor has binding sites for benzodiazepines, barbiturates, and neurosteroids. GABA-A receptors are coupled to chloride ion channels. Therefore, activation of the GABA-A receptor induces increased inward chloride ion flux, resulting in membrane hyperpolarization and neuronal inhibition (PMID: 10561820). After release into the synapse, free GABA that does not bind to either the GABA-A or GABA-B receptor complexes can be taken up by neurons and glial cells. Four different GABA membrane transporter proteins (GAT-1, GAT-2, GAT-3, and BGT-1), which differ in their distribution in the CNS, are believed to mediate the uptake of synaptic GABA into neurons and glial cells. The GABA-A receptor subtype regulates neuronal excitability and rapid changes in fear arousal, such as anxiety, panic, and the acute stress response (PMID: 10561820). Drugs that stimulate GABA-A receptors, such as the benzodiazepines and barbiturates, have anxiolytic and anti-seizure effects via GABA-A-mediated reduction of neuronal excitability, which effectively raises the seizure threshold. GABA-A antagonists produce convulsions in animals and there is decreased GABA-A receptor binding in a positron emission tomography (PET) study of patients with panic disorder. Neurons that produce GABA as their output are called GABAergic neurons and have chiefly inhibitory action at receptors in the vertebrate. Medium spiny neurons (MSNs) are a typical example of inhibitory CNS GABAergic cells. GABA has been shown to have excitatory roles in the vertebrate, most notably in the developing cortex. Organisms synthesize GABA from glutamate using the enzyme L-glutamic acid decarboxylase and pyridoxal phosphate as a cofactor (PMID: 12467378). It is worth noting that this involves converting the principal excitatory neurotransmitter (glutamate) into the principal inhibitory one (GABA). Drugs that act as agonists of GABA receptors (known as GABA analogs or GABAergic drugs), or increase the available amount of GABA typically have relaxing, anti-anxiety, and anti-convulsive effects. GABA is found to be deficient in cerebrospinal fluid and the brain in many studies of experimental and human epilepsy. Benzodiazepines (such as Valium) are useful in status epilepticus because they act on GABA receptors. GABA increases in the brain after administration of many seizure medications. Hence, GABA is clearly an antiepileptic nutrient. Inhibitors of GAM metabolism can also produce convulsions. Spasticity and involuntary movement syndromes, such as Parkinsons, Friedreichs ataxia, tardive dyskinesia, and Huntingtons chorea, are all marked by low GABA when amino acid levels are studied. Trials of 2 to 3 g of GABA given orally have been effective in various epilepsy and spasticity syndromes. Agents that elevate GABA are als... Gamma-aminobutyric acid, also known as gaba or 4-aminobutanoic acid, belongs to gamma amino acids and derivatives class of compounds. Those are amino acids having a (-NH2) group attached to the gamma carbon atom. Thus, gamma-aminobutyric acid is considered to be a fatty acid lipid molecule. Gamma-aminobutyric acid is soluble (in water) and a weakly acidic compound (based on its pKa). Gamma-aminobutyric acid can be synthesized from butyric acid. Gamma-aminobutyric acid is also a parent compound for other transformation products, including but not limited to, (1S,2S,5S)-2-(4-glutaridylbenzyl)-5-phenylcyclohexan-1-ol, 4-(methylamino)butyric acid, and pregabalin. Gamma-aminobutyric acid can be found in a number of food items such as watercress, sour cherry, peach, and cardoon, which makes gamma-aminobutyric acid a potential biomarker for the consumption of these food products. Gamma-aminobutyric acid can be found primarily in most biofluids, including urine, cerebrospinal fluid (CSF), blood, and feces, as well as throughout most human tissues. Gamma-aminobutyric acid exists in all living species, ranging from bacteria to humans. In humans, gamma-aminobutyric acid is involved in a couple of metabolic pathways, which include glutamate metabolism and homocarnosinosis. Gamma-aminobutyric acid is also involved in few metabolic disorders, which include 2-hydroxyglutric aciduria (D and L form), 4-hydroxybutyric aciduria/succinic semialdehyde dehydrogenase deficiency, hyperinsulinism-hyperammonemia syndrome, and succinic semialdehyde dehydrogenase deficiency. Moreover, gamma-aminobutyric acid is found to be associated with alzheimers disease, hyper beta-alaninemia, tuberculous meningitis, and hepatic encephalopathy. Gamma-aminobutyric acid is a non-carcinogenic (not listed by IARC) potentially toxic compound. gamma-Aminobutyric acid (γ-Aminobutyric acid) (GABA ) is the chief inhibitory neurotransmitter in the mammalian central nervous system. Its principal role is reducing neuronal excitability throughout the nervous system. In humans, GABA is also directly responsible for the regulation of muscle tone . Chronically high levels of GABA are associated with at least 5 inborn errors of metabolism including: D-2-Hydroxyglutaric Aciduria, 4-Hydroxybutyric Aciduria/Succinic Semialdehyde Dehydrogenase Deficiency, GABA-Transaminase Deficiency, Homocarnosinosis and Succinic semialdehyde dehydrogenase deficiency (T3DB). [Spectral] 4-Aminobutanoate (exact mass = 103.06333) and D-2-Aminobutyrate (exact mass = 103.06333) were not completely separated on HPLC under the present analytical conditions as described in AC$XXX. Additionally some of the peaks in this data contains dimers and other unidentified ions. Acquisition and generation of the data is financially supported in part by CREST/JST. COVID info from clinicaltrial, clinicaltrials, clinical trial, clinical trials D018377 - Neurotransmitter Agents > D018682 - GABA Agents KEIO_ID A002 Corona-virus Coronavirus SARS-CoV-2 COVID-19 SARS-CoV COVID19 SARS2 SARS γ-Aminobutyric acid (4-Aminobutyric acid) is a major inhibitory neurotransmitter in the adult mammalian brain, binding to the ionotropic GABA receptors (GABAA receptors) and metabotropic receptors (GABAB receptors. γ-Aminobutyric acid shows calming effect by blocking specific signals of central nervous system[1][2]. γ-Aminobutyric acid (4-Aminobutyric acid) is a major inhibitory neurotransmitter in the adult mammalian brain, binding to the ionotropic GABA receptors (GABAA receptors) and metabotropic receptors (GABAB receptors. γ-Aminobutyric acid shows calming effect by blocking specific signals of central nervous system[1][2]. γ-Aminobutyric acid (4-Aminobutyric acid) is a major inhibitory neurotransmitter in the adult mammalian brain, binding to the ionotropic GABA receptors (GABAA receptors) and metabotropic receptors (GABAB receptors. γ-Aminobutyric acid shows calming effect by blocking specific signals of central nervous system[1][2].

N-acetylcitrulline

C8H15N3O4 (217.106251)

N-alpha-Acetyl-L-citrulline, also known as N-acetylcitrulline, is an N-acetylated metabolite of citrulline that is part of the arginine biosynthetic pathway. Arginine biosynthesis is notable for its complexity and variability at the genetic level, and by its connection with several other pathways, such as pyrimidine and polyamine biosynthesis, and certain degradative pathways. The initial steps of the arginine biosynthetic pathways proceed via N-acetylated intermediates. The presumed reason for this is that the acetylation prevents the spontaneous cyclization of glutamate derivatives, which leads to proline biosynthesis. N-acetyl-L-ornithine can be transcarbamylated directly by the enzyme acetylornithine transcarbamylase, resulting in N-acetyl-L-citrulline. The enzyme acetylornithine deacetylase can accept N-acetyl-L-citrulline as a substrate and can deacetylate it into citrulline. N-alpha-Acetyl-L-citrulline is found in cases of deficiency of the urea cycle enzyme argininosuccinate synthase (EC 6.3.4.5) that leads to increased concentrations of citrulline and N-acetylcitrulline in the urine (PMID: 14633929). N-acetyl-l-citrulline, also known as (S)-2-acetamido-5-ureidopentanoic acid, is a member of the class of compounds known as N-acyl-l-alpha-amino acids. N-acyl-l-alpha-amino acids are n-acylated alpha amino acids which have the L-configuration of the alpha-carbon atom. N-acetyl-l-citrulline is slightly soluble (in water) and a weakly acidic compound (based on its pKa). N-acetyl-l-citrulline can be found in a number of food items such as macadamia nut, persian lime, broccoli, and annual wild rice, which makes N-acetyl-l-citrulline a potential biomarker for the consumption of these food products.

1-Methylhistamine

C6H11N3 (125.0952926)

1-Methylhistamine, also known as H137, belongs to the class of organic compounds known as 2-arylethylamines. These are primary amines that have the general formula RCCNH2, where R is an organic group. 1-Methylhistamine exists in all living organisms, ranging from bacteria to humans. Within humans, 1-methylhistamine participates in a number of enzymatic reactions. In particular, S-adenosylhomocysteine and 1-methylhistamine can be biosynthesized from S-adenosylmethionine and histamine; which is mediated by the enzyme histamine N-methyltransferase. In addition, 1-methylhistamine can be converted into methylimidazole acetaldehyde through its interaction with the enzyme amine oxidase [flavin-containing] a. In humans, 1-methylhistamine is involved in histidine metabolism. 1-Methylhistamine is a potentially toxic compound. 1-Methylhistamine is a histamine metabolite. It is a product of histamine 1-methyltransferase [EC 2.1.1.8] in the pathway histidine metabolism (KEGG). [HMDB] Acquisition and generation of the data is financially supported in part by CREST/JST. D004791 - Enzyme Inhibitors

Sarcosine

C3H7NO2 (89.0476762)

Sarcosine is the N-methyl derivative of glycine. Sarcosine is metabolized to glycine by the enzyme sarcosine dehydrogenase, while glycine-N-methyl transferase generates sarcosine from glycine. Sarcosine is a natural amino acid found in muscles and other body tissues. In the laboratory it may be synthesized from chloroacetic acid and methylamine. Sarcosine is naturally found in the metabolism of choline to glycine. Sarcosine is sweet to the taste and dissolves in water. It is used in manufacturing biodegradable surfactants and toothpastes as well as in other applications. Sarcosine is ubiquitous in biological materials and is present in such foods as egg yolks, turkey, ham, vegetables, legumes, etc. Sarcosine is formed from dietary intake of choline and from the metabolism of methionine, and is rapidly degraded to glycine. Sarcosine has no known toxicity, as evidenced by the lack of phenotypic manifestations of sarcosinemia, an inborn error of sarcosine metabolism. Sarcosinemia can result from severe folate deficiency because of the folate requirement for the conversion of sarcosine to glycine (Wikipedia). Sarcosine has recently been identified as a biomarker for invasive prostate cancer. It was found to be greatly increased during prostate cancer progression to metastasis and could be detected in urine. Sarcosine levels were also increased in invasive prostate cancer cell lines relative to benign prostate epithelial cells (PMID: 19212411). Sarcosine, also known as N-methylglycine or (methylamino)acetic acid, is a member of the class of compounds known as alpha amino acids. Alpha amino acids are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon). Sarcosine is soluble (in water) and a moderately acidic compound (based on its pKa). Sarcosine can be found in peanut, which makes sarcosine a potential biomarker for the consumption of this food product. Sarcosine can be found primarily in most biofluids, including blood, saliva, cerebrospinal fluid (CSF), and feces, as well as in human muscle, prostate and skeletal muscle tissues. Sarcosine exists in all living organisms, ranging from bacteria to humans. In humans, sarcosine is involved in few metabolic pathways, which include glycine and serine metabolism, methionine metabolism, and sarcosine oncometabolite pathway. Sarcosine is also involved in several metabolic disorders, some of which include homocystinuria-megaloblastic anemia due to defect in cobalamin metabolism, cblg complementation type, hyperglycinemia, non-ketotic, hypermethioninemia, and dimethylglycine dehydrogenase deficiency. Moreover, sarcosine is found to be associated with sarcosinemia. Sarcosine is a non-carcinogenic (not listed by IARC) potentially toxic compound. Sarcosine. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=107-97-1 (retrieved 2024-07-01) (CAS RN: 107-97-1). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). Sarcosine (N-Methylglycine), an endogenous amino acid, is a competitive glycine transporter type I (GlyT1) inhibitor and N-methyl-D-aspartate (NMDA) receptor co-agonist. Sarcosine increases the glycine concentration, resulting in an indirect potentiation of the NMDA receptor. Sarcosine is commonly used for the research of schizophrenia[1][2]. Sarcosine (N-Methylglycine), an endogenous amino acid, is a competitive glycine transporter type I (GlyT1) inhibitor and N-methyl-D-aspartate (NMDA) receptor co-agonist. Sarcosine increases the glycine concentration, resulting in an indirect potentiation of the NMDA receptor. Sarcosine is commonly used for the research of schizophrenia[1][2].

Beta-Alanine

C3H7NO2 (89.0476762)

beta-Alanine is the only naturally occurring beta-amino acid - an amino acid in which the amino group is at the beta-position from the carboxylate group. It is formed in vivo by the degradation of dihydrouracil and carnosine. It is a component of the naturally occurring peptides carnosine and anserine and also of pantothenic acid (vitamin B-5), which itself is a component of coenzyme A. Under normal conditions, beta-alanine is metabolized into acetic acid. beta-Alanine can undergo a transanimation reaction with pyruvate to form malonate-semialdehyde and L-alanine. The malonate semialdehyde can then be converted into malonate via malonate-semialdehyde dehydrogenase. Malonate is then converted into malonyl-CoA and enter fatty acid biosynthesis. Since neuronal uptake and neuronal receptor sensitivity to beta-alanine have been demonstrated, beta-alanine may act as a false transmitter replacing gamma-aminobutyric acid. When present in sufficiently high levels, beta-alanine can act as a neurotoxin, a mitochondrial toxin, and a metabotoxin. A neurotoxin is a compound that damages the brain or nerve tissue. A mitochondrial toxin is a compound that damages mitochondria and reduces cellular respiration as well as oxidative phosphorylation. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of beta-alanine are associated with at least three inborn errors of metabolism, including GABA-transaminase deficiency, hyper-beta-alaninemia, and methylmalonate semialdehyde dehydrogenase deficiency. beta-Alanine is a central nervous system (CNS) depressant and is an inhibitor of GABA transaminase. The associated inhibition of GABA transaminase and displacement of GABA from CNS binding sites can also lead to GABAuria (high levels of GABA in the urine) and convulsions. In addition to its neurotoxicity, beta-alanine reduces cellular levels of taurine, which are required for normal respiratory chain function. Cellular taurine depletion is known to reduce respiratory function and elevate mitochondrial superoxide generation, which damages mitochondria and increases oxidative stress (PMID: 27023909). Individuals suffering from mitochondrial defects or mitochondrial toxicity typically develop neurotoxicity, hypotonia, respiratory distress, and cardiac failure. beta-Alanine is a biomarker for the consumption of meat, especially red meat. Widely distributed in plants including algae, fungi and many higher plants. Flavouring ingredient β-Alanine. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=107-95-9 (retrieved 2024-07-01) (CAS RN: 107-95-9). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). β-Alanine is a non-essential amino acid that is shown to be metabolized into carnosine, which functions as an intracellular buffer. β-Alanine is a non-essential amino acid that is shown to be metabolized into carnosine, which functions as an intracellular buffer. β-Alanine is a non-essential amino acid that is shown to be metabolized into carnosine, which functions as an intracellular buffer.

Phosphoserine

C3H8NO6P (185.0089238)

The phosphoric acid ester of serine. As a constituent (residue) of proteins, its side chain can undergo O-linked glycosylation. This might be important in explaining some of the devastating consequences of diabetes. It is one of three amino acid residues that are commonly phosphorylated by kinases during cell signalling in eukaryotes. Phosphorylated serine residues are often referred to as phosphoserine. Serine proteases are a common type of protease. Serine, organic compound, one of the 20 amino acids commonly found in animal proteins. Only the L-stereoisomer appears in mammalian protein. It is not essential to the human diet, since it can be synthesized in the body from other metabolites, including glycine. Serine was first obtained from silk protein, a particularly rich source, in 1865. Its name is derived from the Latin for silk, sericum. Serines structure was established in 1902. [HMDB] Phosphoserine is the phosphoric acid ester of the amino acid serine. It is found in essentially all living organisms ranging from microbes to plants to mammals. Phosphoserine is a component of many proteins as the result of posttranslational modifications to the native protein’s serine residue(s). The phosphorylation of the hydroxyl functional group in serine to produce phosphoserine is catalyzed by various types of kinases. Serine is one of three amino acid residues that are commonly phosphorylated by kinases during cell signalling in eukaryotes. Free phosphoserine is found in many biofluids and likely arises from the proteolysis of proteins containing phosphoserine residues (PMID: 7693088). Acquisition and generation of the data is financially supported in part by CREST/JST. KEIO_ID P060 DL-O-Phosphoserine, a normal metabolite in human biofluid, is an ester of serine and phosphoric acid.

Methionine sulfoximine

C5H12N2O3S (180.0568602)

Methionine sulfoximine is found in flours treated with NCl3 as a produced of NCl3 action on wheat protein

Cysteineglutathione disulfide

C13H22N4O8S2 (426.0879012)

Cysteineglutathione disulfide is a molecule that is formed upon oxidative stress of glutathione, that will form mixed disulfides with protein thiol groups, causing reversible S-glutathionylation. S-glutathionylation is an important post-translational modification responsible for transducing oxidant signals. S-glutathionylation of thiols confers protection against their irreversible oxidation, like for instance the formation of sulphonic acid moieties. If the targeted cysteine is a functionally critical amino acid, S-glutathionylation will however also modify protein function. (PMID 16515838). S-sulfonation and S-thiolation of transthyretin Phe33Cys has been detected in a patient with familial transthyretin amyloidosis. (PMID 12876326). In Cystinotic human skin fibroblasts in tissue culture there is an accumulation of cystine. Stored cystine in cystinotic tissues may derive in part from glutathione-cysteine mixed disulfide via transpeptidation. (PMID 6130452). Cystinosis is an autosomal recessive disorder caused by an impaired transport of cystine out of lysosomes. (PMID 15042893). Cysteineglutathione disulfide is a molecule that is formed upon oxidative stress of glutathione, that will form mixed disulfides with protein thiol groups, causing reversible S-glutathionylation. [HMDB]

Gamma-glutamylglutamate

C10H16N2O7 (276.0957466)

gammaGlutamylglutamic acid is made of two glutamic acid molecules. Glutamic acid (Glu), also referred to as glutamate (the anion), is one of the 20 proteinogenic amino acids. It is not among the essential amino acids. Glutamate is a key molecule in cellular metabolism. In humans, dietary proteins are broken down by digestion into amino acids, which serves as metabolic fuel or other functional roles in the body. Glutamate is the most abundant fast excitatory neurotransmitter in the mammalian nervous system. At chemical synapses, glutamate is stored in vesicles. Nerve impulses trigger release of glutamate from the pre-synaptic cell. In the opposing post-synaptic cell, glutamate receptors, such as the NMDA receptor, bind glutamate and are activated. Because of its role in synaptic plasticity, it is believed that glutamic acid is involved in cognitive functions like learning and memory in the brain. Glutamate transporters are found in neuronal and glial membranes. They rapidly remove glutamate from the extracellular space. In brain injury or disease, they can work in reverse and excess glutamate can accumulate outside cells. This process causes calcium ions to enter cells via NMDA receptor channels, leading to neuronal damage and eventual cell death, and is called excitotoxicity. The mechanisms of cell death include: * Damage to mitochondria from excessively high intracellular Ca2+. * Glu/Ca2+-mediated promotion of transcription factors for pro-apoptotic genes, or downregulation of transcription factors for anti-apoptotic genes. Excitotoxicity due to glutamate occurs as part of the ischemic cascade and is associated with stroke and diseases like amyotrophic lateral sclerosis, lathyrism, and Alzheimers disease. glutamic acid has been implicated in epileptic seizures. Microinjection of glutamic acid into neurons produces spontaneous depolarization around one second apart, and this firing pattern is similar to what is known as paroxysmal depolarizing shift in epileptic attacks. This change in the resting membrane potential at seizure foci could cause spontaneous opening of voltage activated calcium channels, leading to glutamic acid release and further depolarization. (http://en.wikipedia.org/wiki/Glutamic_acid) [HMDB] gamma-Glutamylglutamic acid is a dipeptide composed of gamma-glutamate and glutamic acid. Glutamic acid (Glu), also referred to as glutamate (the anion), is one of the 20 proteinogenic amino acids. It is not among the essential amino acids. Glutamate is a key molecule in cellular metabolism. In humans, dietary proteins are broken down by digestion into amino acids, which serve as metabolic fuel and other functional roles in the body. Glutamate is the most abundant fast excitatory neurotransmitter in the mammalian nervous system. At chemical synapses, glutamate is stored in vesicles. Nerve impulses trigger release of glutamate from the pre-synaptic cell. In the opposing post-synaptic cell, glutamate receptors, such as the NMDA receptor, bind glutamate and are activated. Because of its role in synaptic plasticity, it is believed that glutamic acid is involved in cognitive functions like learning and memory in the brain. Glutamate transporters are found in neuronal and glial membranes. They rapidly remove glutamate from the extracellular space. In brain injury or disease, they can work in reverse and excess glutamate can accumulate outside cells. This process causes calcium ions to enter cells via NMDA receptor channels, leading to neuronal damage and eventual cell death, and is called excitotoxicity. The mechanisms of cell death include: (1) damage to mitochondria from excessively high intracellular Ca2+ (2) Glu/Ca2+-mediated promotion of transcription factors for pro-apoptotic genes, or downregulation of transcription factors for anti-apoptotic genes. Excitotoxicity due to glutamate occurs as part of the ischemic cascade and is associated with stroke and diseases like amyotrophic lateral sclerosis, lathyrism, and Alzheimers disease. Glutamic acid has been implicated in epileptic seizures. Microinjection of glutamic acid into neurons produce spontaneous depolarization around one second apart, and this firing pattern is similar to what is known as paroxysmal depolarizing shift in epileptic attacks. This change in the resting membrane potential at seizure foci could cause spontaneous opening of voltage activated calcium channels, leading to glutamic acid release and further depolarization (Wikipedia).

Imidazole propionate

C6H8N2O2 (140.0585748)

Imidazolepropionic acid, also known as deaminohistidine or 4-imidazolylpropionate, belongs to the class of organic compounds known as imidazolyl carboxylic acids and derivatives. These are organic compounds containing a carboxylic acid chain (of at least 2 carbon atoms) linked to an imidazole ring. Imidazolepropionic acid is a very strong basic compound (based on its pKa). Imidazolepropionic acid is a product of histidine metabolism which may involve oxidation or transamination. This compound is found in the urine of rats loaded with histidine (PMID: 6021220). Isolated from the fungus Coprinus atramentarius (common ink cap) Imidazole-5-propionic acid is a histidine metabolite[1].

3-Hydroxyisobutyric acid

C4H8O3 (104.0473418)

(S)-3-Hydroxyisobutyric acid (3-HIBA) (CAS: 2068-83-9) is an organic acid. 3-HIBA is an intermediate in L-valine metabolism. 3-HIBA plays an important role in the diagnosis of the very rare inherited metabolic diseases 3-hydroxyisobutyric aciduria (OMIM: 236795) and methylmalonic semialdehyde dehydrogenase deficiency (OMIM: 603178). Patients with 3-hydroxyisobutyric aciduria excrete a significant amount of 3-HIBA not only during the acute stage but also when stable. 3-Hydroxyisobutyric aciduria is caused by a 3-hydroxyisobutyryl-CoA dehydrogenase deficiency (PMID: 18329219). The severity of this disease varies from case to case. Most patients exhibit dysmorphic features, such as a small triangular face, a long philtrum, low set ears, and micrognathia (PMID: 10686279). Lactic acidemia is also found in the affected patients, indicating that mitochondrial dysfunction is involved. 3-HIBA appears to specifically inhibit the function of the respiratory chain complex I-III and mitochondrial creatine kinase (PMID: 18329219). BioTransformer predicts that 3-HIBA is a product of 2-methylpropanoic acid metabolism via a hydroxylation-of-terminal-methyl reaction catalyzed by CYP2B6 and CYP2E1 enzymes (PMID: 30612223). (S)-3-Hydroxyisobutyric (3-HIBA) acid is an organic acid. 3-HIBA is an intermediate in the metabolic pathways of L-valine and L-thymine amino acids. 3-HIBA plays an important role in the diagnosis of the very rare inherited metabolic diseases 3-hydroxyisobutyric aciduria (OMIM 236795) and methylmalonic semialdehyde dehydrogenase deficiency (OMIM 603178). Patients with 3-hydroxyisobutyric aciduria excrete a significant amount of 3-HIBA not only during the acute stage but also when stable. The deficient enzyme in 3HiB-uria remains unclear. The severity of this disease varies from case to case. Most patients exhibit dysmorphic features, such as a small triangular face, a long philtrum, low set ears and micrognathia (PMID: 113770040, 10686279) [HMDB] 3-Hydroxyisobutyric acid is an important interorgan metabolite, an intermediate in the pathways of l-valine and thymine and a good gluconeogenic substrate.

4-hydroxyglutamate

C5H9NO5 (163.0480704)

4-Hydroxy-L-glutamic acid is an intermediate in the metabolism of gamma-hydroxyglutamic acid. Specifically 4-Hydroxy-L-glutamic acid combines with 2-oxoglutarate to produce 4-hydroxy-2-oxoglutarate and glutamate. The reaction can be described as: 4-Hydroxy-L-glutamate + 2-Oxoglutarate <=> 4-Hydroxy-2-oxoglutarate + L-Glutamate. This reaction is catalyzed by 4-hydroxyglutamate aminotransferase (PMID 13948827). [HMDB] 4-Hydroxy-L-glutamic acid is an intermediate in the metabolism of gamma-hydroxyglutamic acid. Specifically, 4-hydroxy-L-glutamic acid combines with 2-oxoglutarate to produce 4-hydroxy-2-oxoglutarate and glutamate. The reaction can be described as: 4-hydroxy-L-glutamate + 2-oxoglutarate <=> 4-hydroxy-2-oxoglutarate + L-glutamate. This reaction is catalyzed by 4-hydroxyglutamate aminotransferase (PMID: 13948827).

Imidazole lactate

C6H8N2O3 (156.0534898)

Imidazolelactic acid is the component of normal human urine. (PMID: 5856262). histidine loading causes an increase in the excretion of imidazolelactic acid. (PMID: 6021220). During pregnancy the values for imidazolelactic acid in urine is increased 3-fold. An interaction of allergic reactions and anomalies in the metabolism of the sex hormones are considered to form the basis of the pregnancy-specific illnesses that were studied. (PMID: 5789877). Urinary excretion of imidazolelactic acid is also an indication for folic acid and vitamin B12 deficiency. (PMID: 4645251). Imidazolelactic acid is the component of normal human urine. (PMID: 5856262)

Homovanillic acid (HVA)

C9H10O4 (182.057906)

Homovanillic acid (HVA), also known as homovanillate, belongs to the class of organic compounds known as methoxyphenols. Methoxyphenols are compounds containing a methoxy group attached to the benzene ring of a phenol moiety. HVA is also classified as a catechol. HVA is a major catecholamine metabolite that is produced by a consecutive action of monoamine oxidase and catechol-O-methyltransferase on dopamine. HVA is typically elevated in patients with catecholamine-secreting tumors (such as neuroblastoma, pheochromocytoma, and other neural crest tumors). HVA levels are also used in monitoring patients who have been treated for these kinds tumors. HVA levels may also be altered in disorders of catecholamine metabolism such as monoamine oxidase-A (MOA) deficiency. MOA deficiency can cause decreased urinary HVA values, while a deficiency of dopamine beta-hydrolase (the enzyme that converts dopamine to norepinephrine) can cause elevated urinary HVA values. Within humans, HVA participates in a number of enzymatic reactions. In particular, HVA and pyrocatechol can be biosynthesized from 3,4-dihydroxybenzeneacetic acid and guaiacol. This reaction is catalyzed by the enzyme known as catechol O-methyltransferase. In addition, HVA can be biosynthesized from homovanillin through the action of the enzyme known aldehyde dehydrogenase. HVA has recently been found in a number of beers and appears to arise from the fermentation process (https://doi.org/10.1006/fstl.1999.0593). HVA is also a metabolite of Bifidobacterium (PMID: 24958563) and the bacterial breakdown of dietary flavonoids. Dietary flavonols commonly found in tomatoes, onions, and tea, can lead to significantly elevated levels of urinary HVA (PMID: 20933512). Likewise, the microbial digestion of hydroxytyrosol (found in olive oil) can also lead to elevated levels of HVA in humans (PMID: 11929304). Homovanillic acid is a monocarboxylic acid that is the 3-O-methyl ether of (3,4-dihydroxyphenyl)acetic acid. It is a catecholamine metabolite. It has a role as a human metabolite and a mouse metabolite. It is a member of guaiacols and a monocarboxylic acid. It is functionally related to a (3,4-dihydroxyphenyl)acetic acid. It is a conjugate acid of a homovanillate. Homovanillic acid is a natural product found in Aloe africana, Ginkgo biloba, and other organisms with data available. Homovanillic Acid is a monocarboxylic acid that is a catecholamine metabolite. Homovanillic acid may be used a marker for metabolic stress, tobacco usage or the presence of a catecholamine secreting tumor, such as neuroblastoma or pheochromocytoma. Homovanillic acid is a metabolite found in or produced by Saccharomyces cerevisiae. A 3-O-methyl ETHER of (3,4-dihydroxyphenyl)acetic acid. See also: Ipomoea aquatica leaf (part of). Homovanillic acid is a major catecholamine metabolite. 3-Methoxy-4-hydroxyphenylacetic acid is found in beer, olive, and avocado. A monocarboxylic acid that is the 3-O-methyl ether of (3,4-dihydroxyphenyl)acetic acid. It is a catecholamine metabolite. Homovanillic acid is a dopamine metabolite found to be associated with aromatic L-amino acid decarboxylase deficiency, celiac disease, growth hormone deficiency, and sepiapterin reductase deficiency. Homovanillic acid is a dopamine metabolite found to be associated with aromatic L-amino acid decarboxylase deficiency, celiac disease, growth hormone deficiency, and sepiapterin reductase deficiency.

3-Methylhistidine

C7H11N3O2 (169.0851226)

3-Methylhistidine, also known as 3-MHis or 3MH, belongs to the class of organic compounds known as histidine and derivatives. 3MH is also classified as a methylamino acid. Methylamino acids are primarily proteogenic amino acids (found in proteins) which have been methylated (in situ) on their side chains by various methyltransferase enzymes. 3-Methylhistidine is also classified as a member of the class of compounds known as L-alpha-amino acids. L-alpha-Amino acids are alpha amino acids which have the L-configuration of the alpha-carbon atom. Amino acids are organic compounds that contain amino (–NH2) and carboxyl (–COOH) functional groups, along with a side chain (R group) specific to each amino acid. 3-Methylhistidine is generated from histidine residues found in proteins. Histidine can be methylated at either the N1 or N3 position of its imidazole ring, yielding the isomers 1-methylhistidine (1MH; also referred to as pi-methylhistidine) or 3-methylhistidine (3MH; tau-methylhistidine), respectively. There is considerable confusion with regard to the nomenclature of the methylated nitrogen atoms on the imidazole ring of histidine and other histidine-containing peptides such as anserine. In particular, older literature (mostly prior to the year 2000) designated anserine (Npi methylated) as beta-alanyl-N1-methyl-histidine, whereas according to standard IUPAC nomenclature, anserine is correctly named as beta-alanyl-N3-methyl-histidine. As a result, many papers published prior to the year 2000 incorrectly identified 1MH as a specific marker for dietary consumption or various pathophysiological effects when they really were referring to 3MH (PMID: 24137022). Histidine methylation on the 3- or tau site is mediated by the enzyme known as METTL18. METTL18 is a nuclear methyltransferase protein that contains a functional nuclear localization signal and accumulates in nucleoli. Urinary concentrations of 3-methylhistidine can be used as a biomarker for skeletal muscle protein breakdown in humans who have been subject to muscle injury (PMID: 16079625). 3-methylhistidine is formed by the posttranslational methylation of histidine residues of the main myofibrillar proteins actin and myosin. During protein catabolism, 3-methylhistidine is released but cannot be reutilized. Therefore, the plasma concentration and urine excretion of 3-methylhistidine are sensitive markers of myofibrillar protein degradation (PMID: 32235743). Approximately 75\\\% of 3-methylhistidine is estimated to originate from skeletal muscle (PMID: 32235743). In addition to the degradation of muscle proteins, the 3-methylhistidine level is affected by the degradation of intestinal proteins and meat intake. 3-Methylhistidine exists in all eukaryotes, ranging from yeast to humans. In humans, 3-methylhistidine is involved in methylhistidine metabolism. 3-Methylhistidine has been found to be associated with several diseases such as diabetes mellitus type 2, eosinophilic esophagitis, and kidney disease. The normal concentration of 3-methylhistidine in the urine of healthy adult humans has been detected and quantified in a range of 3.63–69.27 micromoles per millimole (umol/mmol) of creatinine, with most studies reporting the average urinary concentration between 15–20 umol/mmol of creatinine. The average concentration of 3-methylhistidine in human blood plasma has been detected and quantified at 2.85 micromolar (uM) with a range of 0.0–5.9 uM. As a general rule, urinary 1MH is associated with white meat intake (p< 0.001), whereas urinary 3MH is associated with red meat intake (p< 0.001) (PMID: 34091671). 3-Methyl-L-histidine is a biomarker for meat consumption, especially chicken. It is also a biomarker for the consumption of soy products.

N-acetyltyrosine

C11H13NO4 (223.0844538)

N-Acetyl-L-tyrosine or N-Acetyltyrosine, belongs to the class of organic compounds known as N-acyl-alpha amino acids. N-acyl-alpha amino acids are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. N-Acetyltyrosine can also be classified as an alpha amino acid or a derivatized alpha amino acid. Technically, N-Acetyltyrosine is a biologically available N-terminal capped form of the proteinogenic alpha amino acid L-tyrosine. N-acetyl amino acids can be produced either via direct synthesis of specific N-acetyltransferases or via the proteolytic degradation of N-acetylated proteins by specific hydrolases. N-terminal acetylation of proteins is a widespread and highly conserved process in eukaryotes that is involved in protection and stability of proteins (PMID: 16465618). About 85\\\% of all human proteins and 68\\\% of all yeast proteins are acetylated at their N-terminus (PMID: 21750686). Several proteins from prokaryotes and archaea are also modified by N-terminal acetylation. The majority of eukaryotic N-terminal-acetylation reactions occur through N-acetyltransferase enzymes or NAT’s (PMID: 30054468). These enzymes consist of three main oligomeric complexes NatA, NatB, and NatC, which are composed of at least a unique catalytic subunit and one unique ribosomal anchor. The substrate specificities of different NAT enzymes are mainly determined by the identities of the first two N-terminal residues of the target protein. The human NatA complex co-translationally acetylates N-termini that bear a small amino acid (A, S, T, C, and occasionally V and G) (PMID: 30054468). NatA also exists in a monomeric state and can post-translationally acetylate acidic N-termini residues (D-, E-). NatB and NatC acetylate N-terminal methionine with further specificity determined by the identity of the second amino acid. N-acetylated amino acids, such as N-acetyltyrosine can be released by an N-acylpeptide hydrolase from peptides generated by proteolytic degradation (PMID: 16465618). In addition to the NAT enzymes and protein-based acetylation, N-acetylation of free tyrosine can also occur. Many N-acetylamino acids, including N-acetyltyrosine are classified as uremic toxins if present in high abundance in the serum or plasma (PMID: 26317986; PMID: 20613759). Uremic toxins are a diverse group of endogenously produced molecules that, if not properly cleared or eliminated by the kidneys, can cause kidney damage, cardiovascular disease and neurological deficits (PMID: 18287557). N-Acetyl-L-tyrosine, has also been associated with several inborn metabolic disorders including tyrosinemia I and aromatic l-amino acid decarboxylase deficiency. N-acetyltyrosine, is used in place of as a tyrosine precursor and administered as a source of nutritional support where oral nutrition is inadequate or cannot be tolerated (PMID: 14621123). N-acetyltyrosine has also been identified as an endogenous stress response factor. Under stress conditions, mitochondria release low levels of reactive oxygen species (ROS), which triggers a cytoprotective response, called "mitohormesis". N-acetyltyrosine has recently been identified as an intrinsic triggering factor of mitohormesis in stressed animals (PMID: 32118349). Interventions and small molecules, which promote formation of reactive oxygen species (ROS), have been shown to increase stress resistance and lifespan of different model organisms. These phenotypes occur only in response to low concentrations of ROS, while higher concentrations of ROS exert opposing effects. In this regard, a stress-dependent increase in N-acetyltyrosine was recently found to occur in insect larvae that had endured high temperatures (i.e. thermal stress). N-acetyltyrosine treatment has also been demonstrated to induce thermotolerance in several tested insect species. N-acetyltyrosine has been identified in the serum of humans as well as mice, and its concentration in mice was shown to be increased by heat s... Acetyltyrosine is a side chain reaction of tyrosine. It converts to tyrosine and then can be used in neurotransmitter treatment as a precursor of cathecholamine (http://www.neuroassist.com/). [HMDB] N-Acetyl-L-tyrosine originates from tyrosine through an AA acetylase, is associated with aromatic L-amino acid decarboxylase deficiency and tyrosinemia I.

Cinnamoylglycine

C11H11NO3 (205.0738896)

Cinnamoylglycine is known as a urinary metabolite in man (PMID 649712) although whether it is formed de novo from plant cinnamate or is a plant product excreted. unchanged has not been conclusively demonstrated. When cinnamoylglycine occurs naturally it is probably a food constituent excreted unchanged. It is not found when small quantities (0.5-6 g) of cinnamic acid are fed to man, but by analogy with animal experiments may be produced when much larger quantities are given. (PMID 6743769). Cinnamoylglycine is known as a urinary metabolite in man (PMID 649712) although whether it is formed de novo from plant cinnamate or is a plant product excreted Cinnamoylglycine is a glycine conjugate of cinnamic acid and a urinary metabolite in human. Cinnamoylglycine is used as a potential urinary biomarker indicating intact or disrupted colonization resistance during and after antibiotic treatment[1].

N-Acetylglutamine

C7H12N2O4 (188.07970319999998)

N-Acetyl-L-glutamine (NAcGln) or N-Acetylglutamine, belongs to the class of organic compounds known as N-acyl-alpha amino acids. N-acyl-alpha amino acids are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. N-Acetylglutamine can also be classified as an alpha amino acid or a derivatized alpha amino acid. Technically, N-Acetylglutamine is a biologically available N-terminal capped form of the proteinogenic alpha amino acid L-glutamine. N-acetyl amino acids can be produced either via direct synthesis of specific N-acetyltransferases or via the proteolytic degradation of N-acetylated proteins by specific hydrolases. N-terminal acetylation of proteins is a widespread and highly conserved process in eukaryotes that is involved in protection and stability of proteins (PMID: 16465618). About 85\\\% of all human proteins and 68\\\% of all yeast proteins are acetylated at their N-terminus (PMID: 21750686). Several proteins from prokaryotes and archaea are also modified by N-terminal acetylation. The majority of eukaryotic N-terminal-acetylation reactions occur through N-acetyltransferase enzymes or NAT‚Äôs (PMID: 30054468). These enzymes consist of three main oligomeric complexes NatA, NatB, and NatC, which are composed of at least a unique catalytic subunit and one unique ribosomal anchor. The substrate specificities of different NAT enzymes are mainly determined by the identities of the first two N-terminal residues of the target protein. The human NatA complex co-translationally acetylates N-termini that bear a small amino acid (A, S, T, C, and occasionally V and G) (PMID: 30054468). NatA also exists in a monomeric state and can post-translationally acetylate acidic N-termini residues (D-, E-). NatB and NatC acetylate N-terminal methionine with further specificity determined by the identity of the second amino acid. N-acetylated amino acids, such as N-acetylglutamine can be released by an N-acylpeptide hydrolase from peptides generated by proteolytic degradation (PMID: 16465618). In addition to the NAT enzymes and protein-based acetylation, N-acetylation of free glutamine can also occur. In particular, N-Acetylglutamine can be biosynthesized from L-glutamine and acetyl-CoA by the enzyme glutamine N-acyltransferase (EC 2.3.1.68). Excessive amounts N-acetyl amino acids including N-acetylglutamine (as well as N-acetylglycine, N-acetylserine, N-acetylmethionine, N-acetylglutamate, N-acetylalanine, N-acetylleucine and smaller amounts of N-acetylthreonine, N-acetylisoleucine, and N-acetylvaline) can be detected in the urine with individuals with acylase I deficiency, a genetic disorder (PMID: 16465618). Aminoacylase I is a soluble homodimeric zinc binding enzyme that catalyzes the formation of free aliphatic amino acids from N-acetylated precursors. In humans, Aminoacylase I is encoded by the aminoacylase 1 gene (ACY1) on chromosome 3p21 that consists of 15 exons (OMIM 609924). Individuals with aminoacylase I deficiency will experience convulsions, hearing loss and difficulty feeding (PMID: 16465618). ACY1 can also catalyze the reverse reaction, the synthesis of acetylated amino acids. Many N-acetylamino acids, including N-acetylglutamine are classified as uremic toxins if present in high abundance in the serum or plasma (PMID: 26317986; PMID: 20613759). Uremic toxins are a diverse group of endogenously produced molecules that, if not properly cleared or eliminated by the kidneys, can cause kidney damage, cardiovascular disease and neurological deficits (PMID: 18287557). N-acetylglutamine can be used for parenteral nutrition as a source of glutamine since glutamine is too unstable whereas N-acetylglutamine is very stable. In patients treated with aminoglycosides and/or glycopeptides, an elevation of N-acetylglutamine in urine suggests renal tubular injury. N-Acetylglutamine (GIcNAc) is a modified amino acid (an acetylated analogue of glutamine), a metabolite present in normal human urine. The decomposition products of GIcNAc have been identified by NMR and HPLC-MS as N-acetyl-L-glutamic acid, N-(2,6-dioxo-3-piperidinyl) acetamide, pyroglutamic acid, glutamic acid, and glutamine. GIcNAc is used for parenteral nutrition as a source of glutamine, since glutamine is too unstable, but GIcNAc is very stable. In patients treated with aminoglycosides and/or glycopeptides, elevation GIcNAc in urine suggests renal tubular injury. High amounts of N-acetylated amino acids (i.e.: N-Acetylglutamine) were detected patient with aminoacylase I deficiency (EC 3.5.1.14, a homodimeric zinc-binding metalloenzyme located in the cytosol), a novel inborn error of metabolism. (PMID: 15331932, 11312773, 7952062, 2569664, 16274666) [HMDB] C78272 - Agent Affecting Nervous System > C47795 - CNS Stimulant Aceglutamide (α-N-Acetyl-L-glutamine) is a psychostimulant and nootropic, used to improve memory and concentration[1].

N-Acetylserine

C5H9NO4 (147.0531554)

N-Acetyl-L-serine or N-Acetylserine, belongs to the class of organic compounds known as N-acyl-alpha amino acids. N-acyl-alpha amino acids are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. N-Acetylserine can also be classified as an alpha amino acid or a derivatized alpha amino acid. Technically, N-Acetylserine is a biologically available N-terminal capped form of the proteinogenic alpha amino acid L-serine. N-acetyl amino acids can be produced either via direct synthesis of specific N-acetyltransferases or via the proteolytic degradation of N-acetylated proteins by specific hydrolases. N-terminal acetylation of proteins is a widespread and highly conserved process in eukaryotes that is involved in protection and stability of proteins (PMID: 16465618). About 85\\% of all human proteins and 68\\% of all yeast proteins are acetylated at their N-terminus (PMID: 21750686). Several proteins from prokaryotes and archaea are also modified by N-terminal acetylation. The majority of eukaryotic N-terminal-acetylation reactions occur through N-acetyltransferase enzymes or NAT’s (PMID: 30054468). These enzymes consist of three main oligomeric complexes NatA, NatB, and NatC, which are composed of at least a unique catalytic subunit and one unique ribosomal anchor. The substrate specificities of different NAT enzymes are mainly determined by the identities of the first two N-terminal residues of the target protein. The human NatA complex co-translationally acetylates N-termini that bear a small amino acid (A, S, T, C, and occasionally V and G) (PMID: 30054468). NatA also exists in a monomeric state and can post-translationally acetylate acidic N-termini residues (D-, E-). NatB and NatC acetylate N-terminal methionine with further specificity determined by the identity of the second amino acid. N-acetylated amino acids, such as N-acetylserine can be released by an N-acylpeptide hydrolase from peptides generated by proteolytic degradation (PMID: 16465618). In addition to the NAT enzymes and protein-based acetylation, N-acetylation of free serine can also occur. Excessive amounts N-acetyl amino acids including N-acetylserine (as well as N-acetylglycine, N-acetylglutamine, N-acetylmethionine, N-acetylglutamate, N-acetylalanine, N-acetylleucine and smaller amounts of N-acetylthreonine, N-acetylisoleucine, and N-acetylvaline) can be detected in the urine with individuals with acylase I deficiency, a genetic disorder (PMID: 16465618). Aminoacylase I is a soluble homodimeric zinc binding enzyme that catalyzes the formation of free aliphatic amino acids from N-acetylated precursors. In humans, Aminoacylase I is encoded by the aminoacylase 1 gene (ACY1) on chromosome 3p21 that consists of 15 exons (OMIM 609924). Individuals with aminoacylase I deficiency will experience convulsions, hearing loss and difficulty feeding (PMID: 16465618). ACY1 can also catalyze the reverse reaction, the synthesis of acetylated amino acids. Many N-acetylamino acids, including N-acetylserine are classified as uremic toxins if present in high abundance in the serum or plasma (PMID: 26317986; PMID: 20613759). Uremic toxins are a diverse group of endogenously produced molecules that, if not properly cleared or eliminated by the kidneys, can cause kidney damage, cardiovascular disease and neurological deficits (PMID: 18287557). Acetylation of the N-terminal amino acid (-NH2 acetylation) is a common protein modification in eukaryotes but is rarely encountered in prokaryotes. In mammalians,80 to 90 percent of the cytosolic proteins are subjected to an irreversible, cotranslational amino acid acetylation at their N-terminus. Acetylation of the N-terminal amino acid (-NH2 acetylation) is a common protein modification in eukaryotes but is rarely encountered in prokaryotes. In mammalians, 80 to 90 percent of the cytosolic proteins are subjected to an irreversible, cotranslational amino acid acetylation at their N-terminus. N-acetylated proteins are catabolized in the cytosol by the ATP-ubiquitin-dependent proteasomal pathway. Several types of aminoacylases can be distinguished on the basis of substrate specificity. Aminoacylase I (ACY1; EC 3.5.1.14), the most abundant type, is a soluble homodimeric zinc binding enzyme that catalyzes the formation of free aliphatic amino acids from N-acetylated precursors. It is encoded by the aminoacylase 1 gene (ACY1) on chromosome 3p21 that comprises 15 exons (OMIM 609924). Preferred substrates of ACY1 are aliphatic amino acids with a short-chain acyl moiety, especially N-acetyl-methionine. However, ACY1 can also catalyze the reverse reaction, the synthesis of acetylated amino acids. Functional aminoacylase I is crucial in the last step in this degradation as it catalyzes the hydrolysis of N-acetylated amino acids into acetate and the free amino acid. Although N-acetylation occurs in many metabolic pathways and N-acetylated metabolites are known to accumulate in several inborn errors, there are only a few reports on N-acetylated amino acids detected in urine. Identification of N-acetylated amino acids by routine GC-MS may be problematic for several reasons. The major problem is linked to the identification strategy itself. Identification of an unknown compound in mass spectrometry is usually based on comparison of its spectrum against a library of reference spectra. (PMID: 16465618, 16274666, 17723438). N-Acetyl-L-serine is found in watermelon.

N-acetylcarnosine

C11H16N4O4 (268.1171496)

N-Acetylcarnosine (NAC) is a naturally-occurring compound chemically related to the dipeptide carnosine. Its molecular structure is similar to carnosine with the exception that it carries an additional acetyl group. This makes NAC a more stable molecule which is not easily destroyed by carnosinase, an enzyme that breaks down carnosine to its constituent amino acids, beta-alanine and histidine.; NAC is a free-radical scavenger and is particularly active against lipid peroxidation in the different parts of the lens in the eye. It is the active ingredient of eye drops used in order to prevent or treat cataract. [HMDB] N-Acetylcarnosine (NAC) is a naturally-occurring compound chemically related to the dipeptide carnosine. Its molecular structure is similar to carnosine with the exception that it carries an additional acetyl group. This makes NAC a more stable molecule which is not easily destroyed by carnosinase, an enzyme that breaks down carnosine to its constituent amino acids, beta-alanine and histidine. NAC is a free-radical scavenger and is particularly active against lipid peroxidation in the different parts of the lens in the eye. It is the active ingredient of eye drops used in order to prevent or treat cataract. N-Acetylcarnosine, a natural histidine-containing dipeptide, is a source of pharmacological principal L-carnosine. N-Acetylcarnosine is a potent ophthalmic agent in human cataracts[1].

Hexanoylglycine

C8H15NO3 (173.105188)

Hexanoylglycine is an acyl glycine. Acyl glycines are normally minor metabolites of fatty acids. However, the excretion of certain acyl glycines is increased in several inborn errors of metabolism. In certain cases the measurement of these metabolites in body fluids can be used to diagnose disorders associated with mitochondrial fatty acid beta-oxidation. Acyl glycines are produced through the action of glycine N-acyltransferase (EC 2.3.1.13) which is an enzyme that catalyzes the chemical reaction: acyl-CoA + glycine < -- > CoA + N-acylglycineHexanoylglycine is a fatty acid metabolite, it appears in the urine of patients with hereditary medium-chain acyl-CoA dehydrogenase (MCAD) deficiency (PMID 2775902), which is a genetic disorder. Hexanoylglycine is an acyl glycine. Acyl glycines are normally minor metabolites of fatty acids. However, the excretion of certain acyl glycines is increased in several inborn errors of metabolism. In certain cases the measurement of these metabolites in body fluids can be used to diagnose disorders associated with mitochondrial fatty acid beta-oxidation. Acyl glycines are produced through the action of glycine N-acyltransferase (EC 2.3.1.13) which is an enzyme that catalyzes the chemical reaction:

N-Acetylisoleucine

C8H15NO3 (173.105188)

N-Acetyl-L-isoleucine or N-Acetylisoleucine, belongs to the class of organic compounds known as N-acyl-alpha amino acids. N-acyl-alpha amino acids are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. N-Acetylisoleucine can also be classified as an alpha amino acid or a derivatized alpha amino acid. Technically, N-Acetylisoleucine is a biologically available N-terminal capped form of the proteinogenic alpha amino acid L-isolecuine. N-acetyl amino acids can be produced either via direct synthesis of specific N-acetyltransferases or via the proteolytic degradation of N-acetylated proteins by specific hydrolases. N-terminal acetylation of proteins is a widespread and highly conserved process in eukaryotes that is involved in protection and stability of proteins (PMID: 16465618). About 85\\% of all human proteins and 68\\% of all yeast proteins are acetylated at their N-terminus (PMID: 21750686). Several proteins from prokaryotes and archaea are also modified by N-terminal acetylation. The majority of eukaryotic N-terminal-acetylation reactions occur through N-acetyltransferase enzymes or NAT’s (PMID: 30054468). These enzymes consist of three main oligomeric complexes NatA, NatB, and NatC, which are composed of at least a unique catalytic subunit and one unique ribosomal anchor. The substrate specificities of different NAT enzymes are mainly determined by the identities of the first two N-terminal residues of the target protein. The human NatA complex co-translationally acetylates N-termini that bear a small amino acid (A, S, T, C, and occasionally V and G) (PMID: 30054468). NatA also exists in a monomeric state and can post-translationally acetylate acidic N-termini residues (D-, E-). NatB and NatC acetylate N-terminal methionine with further specificity determined by the identity of the second amino acid. N-acetylated amino acids, such as N-acetylisoleucine can be released by an N-acylpeptide hydrolase from peptides generated by proteolytic degradation (PMID: 16465618). In addition to the NAT enzymes and protein-based acetylation, N-acetylation of free isoleucine can also occur. In particular, N-Acetylisoleucine can be biosynthesized from L-isoleucine and acetyl-CoA by the enzyme leucine/isoleucine N-acetyltransferase (EC 2.3.1.66). Excessive amounts N-acetyl amino acids including N-acetylisoleucine (as well as N-acetylglycine, N-acetylserine, N-acetylglutamine, N-acetylglutamate, N-acetylalanine, N-acetylmethionine and smaller amounts of N-acetylthreonine, N-acetylleucine, and N-acetylvaline) can be detected in the urine with individuals with acylase I deficiency, a genetic disorder (PMID: 16465618). Aminoacylase I is a soluble homodimeric zinc binding enzyme that catalyzes the formation of free aliphatic amino acids from N-acetylated precursors. In humans, Aminoacylase I is encoded by the aminoacylase 1 gene (ACY1) on chromosome 3p21 that consists of 15 exons (OMIM 609924). Individuals with aminoacylase I deficiency will experience convulsions, hearing loss and difficulty feeding (PMID: 16465618). ACY1 can also catalyze the reverse reaction, the synthesis of acetylated amino acids. Many N-acetylamino acids, including N-acetylisoleucine are classified as uremic toxins if present in high abundance in the serum or plasma (PMID: 26317986; PMID: 20613759). Uremic toxins are a diverse group of endogenously produced molecules that, if not properly cleared or eliminated by the kidneys, can cause kidney damage, cardiovascular disease and neurological deficits (PMID: 18287557).

2-aminooctanoate

C8H17NO2 (159.1259222)

DL-2-Aminooctanoic acid, also known as a-aminocaprylate or alpha-aminocaprylic acid, belongs to the class of organic compounds known as alpha amino acids. These are amino acids in which the amino group is attached to the carbon atom immediately adjacent to the carboxylate group (alpha carbon). DL-2-Aminooctanoic acid is a very hydrophobic molecule, practically insoluble in water, and relatively neutral. Outside of the human body, DL-2-Aminooctanoic acid has been detected, but not quantified in cow milk. alpha-Aminooctanoic acid is an amino compound found occasionally in human urine. (PMID: 13447222)

N-acetylarginine

C8H16N4O3 (216.1222346)

N-alpha-Acetyl-L-arginine, also known as N-alpha-acetylarginine, belongs to the class of organic compounds known as N-acyl-alpha amino acids. N-acyl-alpha amino acids are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. N-Acetylarginine can also be classified as an alpha amino acid or a derivatized alpha amino acid. Technically, N-Acetylarginine is a biologically available N-terminal capped form of the proteinogenic alpha amino acid L-arginine. N-acetyl amino acids can be produced either via direct synthesis of specific N-acetyltransferases or via the proteolytic degradation of N-acetylated proteins by specific hydrolases. N-terminal acetylation of proteins is a widespread and highly conserved process in eukaryotes that is involved in protection and stability of proteins (PMID: 16465618). About 85\\\% of all human proteins and 68\\\% of all yeast proteins are acetylated at their N-terminus (PMID: 21750686). Several proteins from prokaryotes and archaea are also modified by N-terminal acetylation. The majority of eukaryotic N-terminal-acetylation reactions occur through N-acetyltransferase enzymes or NAT’s (PMID: 30054468). These enzymes consist of three main oligomeric complexes NatA, NatB, and NatC, which are composed of at least a unique catalytic subunit and one unique ribosomal anchor. The substrate specificities of different NAT enzymes are mainly determined by the identities of the first two N-terminal residues of the target protein. The human NatA complex co-translationally acetylates N-termini that bear a small amino acid (A, S, T, C, and occasionally V and G) (PMID: 30054468). NatA also exists in a monomeric state and can post-translationally acetylate acidic N-termini residues (D-, E-). NatB and NatC acetylate N-terminal methionine with further specificity determined by the identity of the second amino acid. N-acetylated amino acids, such as N-acetylarginine can be released by an N-acylpeptide hydrolase from peptides generated by proteolytic degradation (PMID: 16465618). In addition to the NAT enzymes and protein-based acetylation, N-acetylation of free arginine can also occur. Many N-acetylamino acids, including N-acetylarginine are classified as uremic toxins if present in high abundance in the serum or plasma (PMID: 26317986; PMID: 20613759; PMID: 7777105). Uremic toxins are a diverse group of endogenously produced molecules that, if not properly cleared or eliminated by the kidneys, can cause kidney damage, cardiovascular disease and neurological deficits (PMID: 18287557). N-alpha-Acetyl-L-arginine serum levels (and other guanidino compounds) were elevated of all the hyperargininemic patients are higher than the normal range. Untreated hyperargininemic patients have the highest guanidino compound levels in cerebrospinal fluid. N-alpha-Acetyl-L-arginine is also increased in the urine or hyperargininemic patients. N-alpha-Acetyl-L-arginine is one of the guanidino compounds found elevated in the serum of hemodialyzed renal insufficient (uremic) pediatric patients. N-alpha-Acetylarginine is one of the guanidino compounds found elevated in the serum of an hemodialyzed renal insufficient (uremic) pediatric population. (PMID 7777105) N-Acetyl-L-arginine (Ac-Arg-OH) is one of the guanidino compounds found elevated in the serum of an hemodialyzed renal insufficient (uremic) pediatric population.

3-Methoxytyrosine

C10H13NO4 (211.0844538)

3-Methoxytyrosine, also known as 3-O-methyldopa or vanilalanine, belongs to the class of organic compounds known as tyrosine and derivatives. Tyrosine and derivatives are compounds containing tyrosine or a derivative thereof resulting from reaction of tyrosine at the amino group or the carboxy group, or from the replacement of any hydrogen of glycine by a heteroatom. 3-Methoxytyrosine is one of the main biochemical markers for Aromatic L-amino acid decarboxylase (AADC, EC4.1.1.28) deficiency, an inborn error of metabolism that affects serotonin and dopamine biosynthesis. Chronically high levels of 3-methoxytyrosine are associated with aromatic L-amino acid decarboxylase (AADC, 28) deficiency, an inborn error of metabolism that affects serotonin and dopamine biosynthesis. 3-Methoxytyrosine is a potentially toxic compound. 3-Methoxytyrosine, with regard to humans, has been found to be associated with several diseases such as epilepsy, early-onset, vitamin b6-dependent and pyridoxamine 5-prime-phosphate oxidase deficiency; 3-methoxytyrosine has also been linked to several inborn metabolic disorders including sepiapterin reductase deficiency and aromatic l-amino acid decarboxylase deficiency. 3-Methoxytyrosine is one of the main biochemical markers for Aromatic L-amino acid decarboxylase (AADC, EC 4.1.1.28) deficiency, an inborn error of metabolism that affects serotonin and dopamine biosynthesis. Patients are usually detected in infancy due to developmental delay, hypotonia, and extrapyramidal movements. Diagnosis is based on an abnormal neurotransmitter metabolite profile in CSF and reduced AADC activity in plasma. 3-methoxytyrosine is elevated in CSF, plasma, and urine. (PMID 1357595, 1281049, 16288991) [HMDB] 3-O-Methyldopa (3-Methoxy-L-tyrosine) is a metabolite of L-DOPA which is formed by catechol-O-methyltransferase (COMT). 3-O-Methyldopa competitively inhibits the pharmacodynamics of l-DOPA and dopamine[1]. 3-O-Methyldopa (3-Methoxy-L-tyrosine) is a metabolite of L-DOPA which is formed by catechol-O-methyltransferase (COMT). 3-O-Methyldopa competitively inhibits the pharmacodynamics of l-DOPA and dopamine[1].

2-Piperidinone

C5H9NO (99.0684104)

2-Piperidinone is a derivative of piperidine which is an organic compound. Piperidine is a colorless fuming liquid with an odor described as ammoniacal, pepper-like, the name comes from the genus name Piper, which is the Latin word for pepper. Piperidine is a widely used building block and chemical reagent in the synthesis of organic compounds, including pharmaceuticals.The piperidine structural motif is present in numerous natural alkaloids. These include piperine, which gives black pepper the hot taste. This gave the compound its name. [HMDB] 2-Piperidinone is a derivative of piperidine which is an organic compound. Piperidine is a colorless fuming liquid with an odor described as ammoniacal, pepper-like, the name comes from the genus name Piper, which is the Latin word for pepper. Piperidine is a widely used building block and chemical reagent in the synthesis of organic compounds, including pharmaceuticals.The piperidine structural motif is present in numerous natural alkaloids. These include piperine, which gives black pepper the hot taste. This gave the compound its name. 2-Piperidone is an endogenous metabolite.

N-Acetylasparagine

C6H10N2O4 (174.064054)

N-Acetyl-L-asparagine or N-Acetylasparagine, belongs to the class of organic compounds known as N-acyl-alpha amino acids. N-acyl-alpha amino acids are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. N-Acetylasparagine can also be classified as an alpha amino acid or a derivatized alpha amino acid. Technically, N-Acetylasparagine is a biologically available N-terminal capped form of the proteinogenic alpha amino acid L-asparagine. N-acetyl amino acids can be produced either via direct synthesis of specific N-acetyltransferases or via the proteolytic degradation of N-acetylated proteins by specific hydrolases. N-terminal acetylation of proteins is a widespread and highly conserved process in eukaryotes that is involved in protection and stability of proteins (PMID: 16465618). About 85\\\% of all human proteins and 68\\\% of all yeast proteins are acetylated at their N-terminus (PMID: 21750686). Several proteins from prokaryotes and archaea are also modified by N-terminal acetylation. The majority of eukaryotic N-terminal-acetylation reactions occur through N-acetyltransferase enzymes or NAT’s (PMID: 30054468). These enzymes consist of three main oligomeric complexes NatA, NatB, and NatC, which are composed of at least a unique catalytic subunit and one unique ribosomal anchor. The substrate specificities of different NAT enzymes are mainly determined by the identities of the first two N-terminal residues of the target protein. The human NatA complex co-translationally acetylates N-termini that bear a small amino acid (A, S, T, C, and occasionally V and G) (PMID: 30054468). NatA also exists in a monomeric state and can post-translationally acetylate acidic N-termini residues (D-, E-). NatB and NatC acetylate N-terminal methionine with further specificity determined by the identity of the second amino acid. N-acetylated amino acids, such as N-acetylasparagine can be released by an N-acylpeptide hydrolase from peptides generated by proteolytic degradation (PMID: 16465618). In addition to the NAT enzymes and protein-based acetylation, N-acetylation of free asparagine can also occur. In particular, N-Acetylasparagine can be biosynthesized from L-asparagine and acetyl-CoA by the enzyme NAT1 or the arylamine acetyltransferase I (https://doi.org/10.1096/fasebj.31.1_supplement.821.8). Many N-acetylamino acids are classified as uremic toxins if present in high abundance in the serum or plasma (PMID: 26317986; PMID: 20613759). Uremic toxins are a diverse group of endogenously produced molecules that, if not properly cleared or eliminated by the kidneys, can cause kidney damage, cardiovascular disease and neurological deficits (PMID: 18287557). A human metabolite taken as a putative food compound of mammalian origin [HMDB] (S)-2-acetamido-4-amino-4-oxobutanoic acid is an endogenous metabolite.

Nitro-Tyrosine

C9H10N2O5 (226.058969)

3-Nitrotyrosine, also known as nitrotyrosine is a product of tyrosine nitration mediated by reactive nitrogen species such as peroxynitrite anion and nitrogen dioxide. Nitrotyrosine is identified as an indicator or marker of cell damage, inflammation as well as NO (nitric oxide) production. Nitrotyrosine is formed in the presence of the active metabolite NO. Nitrotyrosine belongs to the class of organic compounds known as tyrosine and derivatives. Tyrosine and derivatives are compounds containing tyrosine or a derivative thereof resulting from reaction of tyrosine at the amino group or the carboxy group, or from the replacement of any hydrogen of glycine by a heteroatom. 3-Nitrotyrosine (NTyr) is formed in vivo in tissue or blood proteins after exposure to nitrosating and/or nitrating agents such as tetranitromethane. (PMID 8319651)

Propionylglycine

C5H9NO3 (131.0582404)

Propionylglycine is an acyl glycine. Acyl glycines are normally minor metabolites of fatty acids. However, the excretion of certain acyl glycines is increased in several inborn errors of metabolism. In certain cases the measurement of these metabolites in body fluids can be used to diagnose disorders associated with mitochondrial fatty acid beta-oxidation. Acyl glycines are produced through the action of glycine N-acyltransferase (EC 2.3.1.13) which is an enzyme that catalyzes the chemical reaction:acyl-CoA + glycine < -- > CoA + N-acylglycineThe level of propionylglycine is elevated in patients with propionic acidemia, which is an inherited deficiency of propionyl-CoA carboxylase. (Disorders of propionate and methylmalonate metabolism. In The Metabolic and Molecular Bases of Inherited Disease). Propionylglycine is an acyl glycine. Acyl glycines are normally minor metabolites of fatty acids. However, the excretion of certain acyl glycines is increased in several inborn errors of metabolism. In certain cases the measurement of these metabolites in body fluids can be used to diagnose disorders associated with mitochondrial fatty acid beta-oxidation. Acyl glycines are produced through the action of glycine N-acyltransferase (EC 2.3.1.13) which is an enzyme that catalyzes the chemical reaction: Propionylglycine is a peptide[1].

Butyrylglycine

C6H11NO3 (145.0738896)

N-Butyrylglycine is an acyl glycine. Acyl glycines are normally minor metabolites of fatty acids. However, the excretion of certain acyl glycines is increased in several inborn errors of metabolism, such as ethylmalonic encephalopathy. In certain cases the measurement of these metabolites in body fluids can be used to diagnose disorders associated with mitochondrial fatty acid beta-oxidation. Acyl glycines are produced through the action of glycine N-acyltransferase (EC 2.3.1.13), which is an enzyme that catalyzes the chemical reaction: acyl-CoA + glycine < -- > CoA + N-acylglycine amino acids composed of glycine substituted at the nitrogen rather than the usual carbon position, resulting in the loss of hydrogen bonding donors. Polymers of these compounds are called Peptoids. N-Butyrylglycine is an acyl glycine. Acyl glycines are normally minor metabolites of fatty acids. However, the excretion of certain acyl glycines is increased in several inborn errors of metabolism. In certain cases the measurement of these metabolites in body fluids can be used to diagnose disorders associated with mitochondrial fatty acid beta-oxidation. Acyl glycines are produced through the action of glycine N-acyltransferase (EC 2.3.1.13) which is an enzyme that catalyzes the chemical reaction:

Glycylphenylalanine

C11H14N2O3 (222.1004374)

Glycyl-Phenylalanine is a dipeptide composed of glycine and phenylalanine. It is an incomplete breakdown product of protein digestion or protein catabolism. Some dipeptides are known to have physiological or cell-signaling effects although most are simply short-lived intermediates on their way to specific amino acid degradation pathways following further proteolysis. This dipeptide has not yet been identified in human tissues or biofluids and so it is classified as an Expected metabolite.

N-Acetylproline

C7H11NO3 (157.0738896)

N-Acetyl-L-proline or N-Acetylproline, belongs to the class of organic compounds known as N-acyl-alpha amino acids. N-acyl-alpha amino acids are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. N-Acetylproline can also be classified as an alpha amino acid or a derivatized alpha amino acid. Technically, N-Acetylproline is a biologically available N-terminal capped form of the proteinogenic alpha amino acid L-proline. N-acetyl amino acids can be produced either via direct synthesis of specific N-acetyltransferases or via the proteolytic degradation of N-acetylated proteins by specific hydrolases. N-terminal acetylation of proteins is a widespread and highly conserved process in eukaryotes that is involved in protection and stability of proteins (PMID: 16465618). About 85\\% of all human proteins and 68\\% of all yeast proteins are acetylated at their N-terminus (PMID: 21750686). Several proteins from prokaryotes and archaea are also modified by N-terminal acetylation. The majority of eukaryotic N-terminal-acetylation reactions occur through N-acetyltransferase enzymes or NAT’s (PMID: 30054468). These enzymes consist of three main oligomeric complexes NatA, NatB, and NatC, which are composed of at least a unique catalytic subunit and one unique ribosomal anchor. The substrate specificities of different NAT enzymes are mainly determined by the identities of the first two N-terminal residues of the target protein. The human NatA complex co-translationally acetylates N-termini that bear a small amino acid (A, S, T, C, and occasionally V and G) (PMID: 30054468). NatA also exists in a monomeric state and can post-translationally acetylate acidic N-termini residues (D-, E-). NatB and NatC acetylate N-terminal methionine with further specificity determined by the identity of the second amino acid. N-acetylated amino acids, such as N-acetylproline can be released by an N-acylpeptide hydrolase from peptides generated by proteolytic degradation (PMID: 16465618). In addition to the NAT enzymes and protein-based acetylation, N-acetylation of free proline can also occur. Many N-acetylamino acids, including N-acetylproline are classified as uremic toxins if present in high abundance in the serum or plasma (PMID: 26317986; PMID: 20613759). Uremic toxins are a diverse group of endogenously produced molecules that, if not properly cleared or eliminated by the kidneys, can cause kidney damage, cardiovascular disease and neurological deficits (PMID: 18287557).

Isobutyrylcarnitine (C4)

C11H21NO4 (231.1470506)

Isobutyryl-L-carnitine is an acylcarnitine. More specifically, it is an isobutyric acid ester of carnitine. Acylcarnitines were first discovered more than 70 year ago (PMID: 13825279). It is believed that there are more than 1000 types of acylcarnitines in the human body. The general role of acylcarnitines is to transport acyl-groups (organic acids and fatty acids) from the cytoplasm into the mitochondria so that they can be broken down to produce energy.  This process is known as beta-oxidation. According to a recent review [Dambrova et al. 2021, Physiological Reviews], acylcarnitines (ACs) can be classified into 9 different categories depending on the type and size of their acyl-group: 1) short-chain ACs; 2) medium-chain ACs; 3) long-chain ACs; 4) very long-chain ACs; 5) hydroxy ACs; 6) branched chain ACs; 7) unsaturated ACs; 8) dicarboxylic ACs and 9) miscellaneous ACs. Short-chain ACs have acyl-groups with two to five carbons (C2-C5), medium-chain ACs have acyl-groups with six to thirteen carbons (C6-C13), long-chain ACs have acyl-groups with fourteen to twenty once carbons (C14-C21) and very long-chain ACs have acyl groups with more than 22 carbons. Isobutyryl-L-carnitine is therefore classified as a short chain AC. As a short-chain acylcarnitine isobutyryl-L-carnitine is a member of the most abundant group of carnitines in the body, comprising more than 50\\\% of all acylcarnitines quantified in tissues and biofluids (PMID: 31920980). Some short-chain carnitines have been studied as supplements or treatments for a number of diseases, including neurological disorders and inborn errors of metabolism. In particular isobutyryl-L-carnitine is elevated in the blood or plasma of individuals with isobutyryl-coa dehydrogenase deficiency (PMID: 20591710), glutaric aciduria type 2 (PMID: 20591710), ethylmalonic encephalopathy (PMID: 20591710), and gestational diabetes mellitus (PMID: 29626588). It is also decreased in the blood or plasma of individuals with traumatic brain injury (PMID: 23560894). Isobutyryl-L-carnitine is elevated in the urine of individuals with glutaric aciduria type 2 (PMID: 2288224), multiple acyl-CoA dehydrogenation deficiency (PMID: 3383426), and acute coronary syndrome (PMID: 30316136). Carnitine acetyltransferase (CrAT, EC:2.3.1.7) is responsible for the synthesis of all short-chain and short branched-chain acylcarnitines (PMID: 23485643). The study of acylcarnitines is an active area of research and it is likely that many novel acylcarnitines will be discovered in the coming years. It is also likely that many novel roles in health and disease will be uncovered. An excellent review of the current state of knowledge for acylcarnitines is available at [Dambrova et al. 2021, Physiological Reviews]. Isobutyryl-L-carnitine is a product of the acyl-CoA dehydrogenases (ACADs), which are a group of mitochondrial enzymes involved in the metabolism of fatty acids or branched-chain amino acids. (OMIM 600301 ) [HMDB] Isobutyrylcarnitine. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=25518-49-4 (retrieved 2024-06-29) (CAS RN: 25518-49-4). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0).

S-methylcysteine

C4H9NO2S (135.0353974)

Methylcysteine is one of the identified number of bioactive substances in garlic that are water soluble (PMID 16484549). It has been suggested that the use of these organosulfur agents derived from garlic could protect partially oxidized and glycated LDL or plasma against further oxidative and glycative deterioration, which might benefit patients with diabetic-related vascular diseases (PMID 15161248). It may also exert some chemopreventive effects on chemical carcinogenesis. However, it should be borne in mind that may also demonstrate promotion potential, depending on the organ examined (PMID 9591199). Methylcystein is a biomarker for the consumption of dried and cooked beans. S-n-methylcysteine, also known as (2r)-2-amino-3-(methylsulfanyl)propanoic acid or 3-(methylthio)-L-alanine, is a member of the class of compounds known as L-cysteine-s-conjugates. L-cysteine-s-conjugates are compounds containing L-cysteine where the thio-group is conjugated. S-n-methylcysteine is soluble (in water) and a moderately acidic compound (based on its pKa). S-n-methylcysteine can be found in soft-necked garlic, which makes S-n-methylcysteine a potential biomarker for the consumption of this food product. S-n-methylcysteine can be found primarily in blood and urine. S-Methyl-L-cysteine is a natural product that acts as a substrate in the catalytic antioxidant system mediated by methionine sulfoxide reductase A (MSRA), with antioxidative, neuroprotective, and anti-obesity activities.

gamma-Glutamyltryptophan

C16H19N3O5 (333.1324644)

gamma-Glutamyltryptophan is a dipeptide composed of gamma-glutamate and tryptophan, and is a proteolytic breakdown product of larger proteins. It belongs to the family of N-acyl-alpha amino acids and derivatives. These are compounds containing an alpha amino acid which bears an acyl group at its terminal nitrogen atom. gamma-Glutamyltryptophan is an incomplete breakdown product of protein digestion or protein catabolism. Some dipeptides are known to have physiological or cell-signaling effects although most are simply short-lived intermediates on their way to specific amino acid degradation pathways following further proteolysis.

3-Methylglutaconate

C6H8O4 (144.0422568)

3-Methylglutaconic acid is an intermediate (as the CoA thioester) in the leucine degradative pathway as well as the mevalonate shunt, a pathway that links isoprenoid metabolism with mitochondrial acetyl-CoA metabolism (PMID: 7603789). 3-methylglutaconyl-CoA hydratase is involved in the metabolism process of 3-methylglutaconic acid. When present in sufficiently high levels, 3-methylglutaconic acid can act as an acidogen and a metabotoxin. An acidogen is an acidic compound that induces acidosis, which has multiple adverse effects on many organ systems. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of 3-methylglutaconic acid are associated with at least five inborn errors of metabolism including 3-hydroxy-3-methylglutaryl-CoA lyase deficiency, 3-methylglutaconic aciduria type I, 3-methylglutaconic aciduria type III, 3-methylglutaconic aciduria type IV, and guanidinoacetate methyltransferase deficiency (GAMT deficiency). 3-Methylglutaconic acid is an organic acid. Abnormally high levels of organic acids in the blood (organic acidemia), urine (organic aciduria), the brain, and other tissues lead to general metabolic acidosis. Acidosis typically occurs when arterial pH falls below 7.35. In infants with acidosis, the initial symptoms include poor feeding, vomiting, loss of appetite, weak muscle tone (hypotonia), and lack of energy (lethargy). These can progress to heart, liver, and kidney abnormalities, seizures, coma, and possibly death. These are also the characteristic symptoms of the untreated IEMs mentioned above. Many affected children with organic acidemias experience intellectual disability or delayed development. In adults, acidosis or acidemia is characterized by headaches, confusion, feeling tired, tremors, sleepiness, and seizures. 3-Methylglutaconic acid is an intermediate (as the CoA thioester) in the leucine degradative pathway as well as the mevalonate shunt, a pathway that links isoprenoid metabolism with mitochondrial acetyl-CoA metabolism. (PMID: 7603789) 3-Methylglutaconic acid is the major metabolites accumulating in 3-Methylglutaconic aciduria (MGTA). 3-Methylglutaconic acid can induce lipid oxidative damage and protein oxidative. 3-Methylglutaconic acid decreases the non-enzymatic antioxidant defenses in cerebral cortex supernatants to elicit oxidative stress in the cerebral cortex. 3-Methylglutaconic acid can be used for brain damage disease research[1].

Asparaginyl-Valine

C9H17N3O4 (231.1219002)

Asparaginyl-Valine is a dipeptide composed of asparagine and valine. It is an incomplete breakdown product of protein digestion or protein catabolism. Some dipeptides are known to have physiological or cell-signaling effects although most are simply short-lived intermediates on their way to specific amino acid degradation pathways following further proteolysis. This dipeptide has not yet been identified in human tissues or biofluids and so it is classified as an Expected metabolite.

(R)-3-Hydroxyisobutyric acid

C4H8O3 (104.0473418)

(R)-3-Hydroxyisobutyric acid (3-HIBA) is an organic acid. The chiral metabolites 3-hydroxyisobutyric acid (HIBA) and 3-aminoisobutyric acid (AIBA) are intermediates in the pathways of L-valine and thymine and play an important role in the diagnosis of the very rare inherited metabolic diseases 3-hydroxyisobutyric aciduria (OMIM: 236795) and methylmalonic semialdehyde dehydrogenase deficiency (OMIM: 603178) (PMID: 10686279). (R)-3-Hydroxyisobutyric acid has been identified in the human placenta (PMID: 32033212). The chiral metabolites 3-hydroxyisobutyric acid (HIBA) and 3-aminoisobutyric acid (AIBA) are intermediates in the pathways of l-valine and thymine and play an important role in the diagnosis of the very rare inherited metabolic diseases 3-hydroxyisobutyric aciduria (OMIM 236795) and methylmalonic semialdehyde dehydrogenase deficiency (OMIM 603178). (PMID 10686279) [HMDB] 3-Hydroxyisobutyric acid is an important interorgan metabolite, an intermediate in the pathways of l-valine and thymine and a good gluconeogenic substrate.

3-hydroxy-2-ethylpropionate

C5H10O3 (118.06299100000001)

Isolated excretion of 2-ethylhydracrylic acid (2-methylbutyrylglycine; 2-MBG) is the hallmark of short/branched-chain acyl-CoA dehydrogenase deficiency (SBCADD), a defect in the proximal pathway of L-isoleucine oxidation (PMID: 15615815). Normal human urine contains small amounts (less than 4 mg/g of creatinine) of 2-ethylhydracrylic acid. Urinary excretion of 2-ethylhydracrylic acid is variably increased in defects of isoleucine oxidation at distal steps in the catabolic pathway (3-oxoacyl-CoA thiolase deficiency and methylmalonyl-CoA mutase deficiency) and is diminished when proximal steps of the oxidative pathway are blocked as in branched-chain oxo acid decarboxylase deficiency (maple syrup urine disease) (PMID: 1016232). 2-Ethylhydracrylic acid has been identified in the human placenta (PMID: 32033212). Isolated excretion of 2-Ethylhydracrylic acid (2-methylbutyrylglycine; 2-MBG) is the hallmark of short/branched-chain acyl-CoA dehydrogenase deficiency (SBCADD), a defect in the proximal pathway of L-isoleucine oxidation (PMID 15615815)

Pi-Methylimidazoleacetic acid

C6H8N2O2 (140.0585748)

Although pi-Methylimidazoleacetic acids isomer (1,4-Methylimidazoleacetic acid) is a known metabolite of Histamine, the origin of N pi-methylimidazoleacetic acid is not certain (PMID 7130180). [HMDB] Although pi-Methylimidazoleacetic acids isomer (1,4-Methylimidazoleacetic acid) is a known metabolite of Histamine, the origin of N pi-methylimidazoleacetic acid is not certain (PMID 7130180).

N-Palmitoylglycine

C18H35NO3 (313.26168000000007)

Palmitoylglycine is an acylglycine with C-16 fatty acid group as the acyl moiety. Acylglycines 1 possess a common amidoacetic acid moiety and are normally minor metabolites of fatty acids. Elevated levels of certain acylglycines appear in the urine and blood of patients with various fatty acid oxidation disorders. They are normally produced through the action of glycine N-acyltransferase which is an enzyme that catalyzes the chemical reaction: acyl-CoA + glycine ↔ CoA + N-acylglycine. Palmitoylglycine is an acylglycine with C-16 fatty acid group as the acyl moiety. Palmitoylglycine (N-palmitoyl glycine), an endogenous lipid that acts as a modulator of calcium influx and nitric oxide (NO) production in sensory neurons[1].

Glutarylcarnitine (C5-DC)

C12H21NO6 (275.13688060000004)

Glutarylcarnitine is an acylcarnitine. More specifically, it is an glutaric acid ester of carnitine. Acylcarnitines were first discovered more than 70 year ago (PMID: 13825279). It is believed that there are more than 1000 types of acylcarnitines in the human body. The general role of acylcarnitines is to transport acyl-groups (organic acids and fatty acids) from the cytoplasm into the mitochondria so that they can be broken down to produce energy.  This process is known as beta-oxidation. According to a recent review [Dambrova et al. 2021, Physiological Reviews], acylcarnitines (ACs) can be classified into 9 different categories depending on the type and size of their acyl-group: 1) short-chain ACs; 2) medium-chain ACs; 3) long-chain ACs; 4) very long-chain ACs; 5) hydroxy ACs; 6) branched chain ACs; 7) unsaturated ACs; 8) dicarboxylic ACs and 9) miscellaneous ACs. Short-chain ACs have acyl-groups with two to five carbons (C2-C5), medium-chain ACs have acyl-groups with six to thirteen carbons (C6-C13), long-chain ACs have acyl-groups with fourteen to twenty once carbons (C14-C21) and very long-chain ACs have acyl groups with more than 22 carbons. Glutarylcarnitine is therefore classified as a short chain AC. As a short-chain acylcarnitine glutarylcarnitine is a member of the most abundant group of carnitines in the body, comprising more than 50\\\% of all acylcarnitines quantified in tissues and biofluids (PMID: 31920980). Some short-chain carnitines have been studied as supplements or treatments for a number of diseases, including neurological disorders and inborn errors of metabolism. Carnitine acetyltransferase (CrAT, EC:2.3.1.7) is responsible for the synthesis of all short-chain and short branched-chain acylcarnitines (PMID: 23485643). Glutarylcarnitine has been identified in the human placenta (PMID: 32033212 ). The study of acylcarnitines is an active area of research and it is likely that many novel acylcarnitines will be discovered in the coming years. It is also likely that many novel roles in health and disease will be uncovered. An excellent review of the current state of knowledge for acylcarnitines is available at [Dambrova et al. 2021, Physiological Reviews]. Glutarylcarnitine is the diagnostic metabolite for malonic aciduria and glutaric aciduria type I monitored in most tandem mass spectrometry newborn screening programmes.

Beta-hydroxyisovaleroylcarnitine

C12H23NO5 (261.1576148)

3-Hydroxyisovalerylcarnitine is structual derivative of 3-hydroxyisovaleric acid and carnitine. Due to its increased concentration in blood, 3-hydroxyisovalerylcarnitine (C5OH-I) is an important indicator for the diagnosis of organic acidemias in newborns (PMID: 18088573). Analysis of acylcarnitines by tandem mass spectrometry (MS/MS) has recently been used to screen newborns for organic acidemias and fatty acid oxidation defects (PMID: 7494654, 9216448, 11427446, 12127323, 14578311). These diseases cause the accumulation of acyl-CoA, which is esterified to acylcarnitine by carnitine acyltransferase. Acylcarnitine is then eliminated in the urine, thus acylcarnitine concentration serves as an excellent indicator for these diseases (PMID: 6361812). 3-Hydroxyisovalerylcarnitine (C5OH-I) is an indicator for diagnoses of multiple carboxylase deficiency (MCD), 3-methylcrotonyl-CoA carboxylase deficiency and 3-hydroxy-3-methylglutaryl-CoA lyase deficiency (PMID: 18088573), which are inborn errors of metabolism.

Acisoga

C9H16N2O2 (184.12117160000003)

N-(3-acetamidopropyl)pyrrolidin-2-one is a catabolic product of spermidine and is formed from N1-acetylspermidine. It is classified as a member of the N-alkylpyrrolidines. N-alkylpyrrolidines are compounds containing a pyrrolidine moiety that is substituted at the N1-position with an alkyl group. Pyrrolidine is a five-membered saturated aliphatic heterocycle with one nitrogen atom and four carbon atoms. N-(3-acetamidopropyl)pyrrolidin-2-one is considered to be soluble (in water) and relatively neutral. (Chemosummarizer) It is excreted in the urine. The urinary level of N-(3-acetamidopropyl)pyrrolidin-2-one is increased in patients with non-Hodgkins lymphoma.

Methionine sulfone

C5H11NO4S (181.0408766)

S-dioxymethionine, also known as (S)-amino-4-(methylsulphonyl)butyric acid or methionine sulfone, is a member of the class of compounds known as L-alpha-amino acids. L-alpha-amino acids are alpha amino acids which have the L-configuration of the alpha-carbon atom. S-dioxymethionine is soluble (in water) and a moderately acidic compound (based on its pKa). S-dioxymethionine can be found in garden onion, which makes S-dioxymethionine a potential biomarker for the consumption of this food product. Methionine sulfone (CAS: 820-10-0), also known as L-methionine-S-dioxide, belongs to the class of organic compounds known as L-alpha-amino acids. These are alpha-amino acids which have the L-configuration at the alpha-carbon atom. Methionine sulfone is a very strong basic compound (based on its pKa). Methionine sulfone has been detected, but not quantified, in garden onions. This could make methionine sulfone a potential biomarker for the consumption of these foods.

C-glycosyltryptophan

C17H22N2O7 (366.1426942)

Tryptophan 2-C-mannoside, also known as 2-alpha-D-mannopyranosyl-L-tryptophan or C-mannosyltryptophan, belongs to the class of organic compounds known as indolyl carboxylic acids and derivatives. Indolyl carboxylic acids and derivatives are compounds containing a carboxylic acid chain (of at least 2 carbon atoms) linked to an indole ring. It is an L-tryptophan derivative and a C-glycosyl compound in which the hydrogen at position 2 on the indole portion has been replaced by an alpha-mannosyl residue. Tryptophan 2-C-mannoside is a very strong basic compound (based on its pKa). Tryptophan 2-C-mannoside has been identified in blood and urine and is a marker of kidney function (PMID: 29234020).

Lanthionine

C6H12N2O4S (208.05177519999998)

Lanthionine is a nonproteinogenic amino acid with the chemical formula (HOOC-CH(NH2)-CH2-S-CH2-CH(NH2)-COOH). It is typically formed by a cysteine residue and a dehydrated serine residue. Despite its name, lanthionine does not contain the element lanthanum. Lanthionine belongs to the class of organic compounds known as L-cysteine-S-conjugates. These are compounds containing L-cysteine where the thio-group is conjugated. Lanthionine is a uremic toxin (PMID: 30087103). In 1941, lanthionine was first isolated by treating wool with sodium carbonate. It was found to be a sulfur-containing amino acid; accordingly it was given the name lanthionine [wool (Latin: Lana), sulfur (Greek: theîon)].[1] Lanthionine was first synthesized by alkylation of cysteine with β-chloroalanine.[2] Lanthionines are found widely in nature. They have been isolated from human hair, lactalbumin, and feathers. Lanthionines have also been found in bacterial cell walls and are the components of a group of gene-encoded peptide antibiotics called lantibiotics, which includes nisin (a food preservative), subtilin, epidermin (effective against Staphylococcus and Streptococcus), and ancovenin (an enzyme inhibitor).[3][4] L-Lanthionine. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=922-55-4 (retrieved 2024-06-29) (CAS RN: 922-55-4). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0).

N-carbamoylalanine

C4H8N2O3 (132.05348980000002)

L-Cysteic acid

C3H7NO5S (169.0044932)

Cysteinesulfonic acid, also known as (2r)-2-amino-3-sulfopropanoic acid or 3-sulfoalanine, is a member of the class of compounds known as L-alpha-amino acids. L-alpha-amino acids are alpha amino acids which have the L-configuration of the alpha-carbon atom. Cysteinesulfonic acid is soluble (in water) and an extremely strong acidic compound (based on its pKa). Cysteinesulfonic acid can be found in a number of food items such as roman camomile, pili nut, chicory, and garden tomato, which makes cysteinesulfonic acid a potential biomarker for the consumption of these food products.

Indolebutyrate

C12H13NO2 (203.0946238)

3-Indolebutyric acid is an indolic tryptophan metabolite occasionally found in human urine. (PMID:7130309). 3-Indolebutyric acid is a plasma and urinary tryptophan-related metabolite related to metabolic and skin diseases. (PMID:15206797). Plasma levels of tryptophan metabolites in the umbilical vein and artery are significantly higher than those in the maternal vein. (PMID:1506727). 3-Indolebutyric acid has been shown to accelerated glucose uptake in the rat diaphragm. (PMID:6025019). 3-Indolebutyric acid is also a microbial netabolite, urinary indole-3-butyrate is produced by Clostridia sp. (PMID:6630445). Indole-3-butyric acid is a indol-3-yl carboxylic acid that is butanoic acid carrying a 1H-indol-3-yl substituent at position 1. It has a role as a plant hormone, a plant metabolite and an auxin. It is functionally related to a butyric acid. It is a conjugate acid of an indole-3-butyrate. Indole-3-butyric acid is a natural product found in Cocos nucifera, Nymphaea alba, and other organisms with data available. Indole-3-butyric acid (IBA) is a plant hormone in the auxin family and is an ingredient in many commercial plant rooting horticultural products. Indole-3-butyric acid is found in common pea, potato, and corn. A indol-3-yl carboxylic acid that is butanoic acid carrying a 1H-indol-3-yl substituent at position 1. Indole-3-butyric acid (3-indolebutyric acid; IBA) is a plant growth auxin and a good rooting agent. It can promote herbs and woody ornamental plant rooting and used for improving fruit rate.

Alanine

C3H7NO2 (89.0476762)

An alpha-amino acid that consists of propionic acid bearing an amino substituent at position 2. Alanine (symbol Ala or A),[4] or α-alanine, is an α-amino acid that is used in the biosynthesis of proteins. It contains an amine group and a carboxylic acid group, both attached to the central carbon atom which also carries a methyl group side chain. Consequently it is classified as a nonpolar, aliphatic α-amino acid. Under biological conditions, it exists in its zwitterionic form with its amine group protonated (as −NH + 3 ) and its carboxyl group deprotonated (as −CO − 2 ). It is non-essential to humans as it can be synthesized metabolically and does not need to be present in the diet. It is encoded by all codons starting with GC (GCU, GCC, GCA, and GCG). The L-isomer of alanine (left-handed) is the one that is incorporated into proteins. L-alanine is second only to L-leucine in rate of occurrence, accounting for 7.8\\\\\% of the primary structure in a sample of 1,150 proteins.[5] The right-handed form, D-alanine, occurs in peptides in some bacterial cell walls[6]: 131  (in peptidoglycan) and in some peptide antibiotics, and occurs in the tissues of many crustaceans and molluscs as an osmolyte. D-Alanine is a weak GlyR (inhibitory glycine receptor) and PMBA agonist, with an EC50 of 9 mM for GlyR. D-Alanine is a weak GlyR (inhibitory glycine receptor) and PMBA agonist, with an EC50 of 9 mM for GlyR. L-Alanine is a non-essential amino acid, involved in sugar and acid metabolism, increases immunity, and provides energy for muscle tissue, brain, and central nervous system. L-Alanine is a non-essential amino acid, involved in sugar and acid metabolism, increases immunity, and provides energy for muscle tissue, brain, and central nervous system.

Glutathione (oxidized)

C20H32N6O12S2 (612.1519552)

Glutathione oxidized (L-Glutathione oxidized) is produced by the oxidation of glutathione. Detoxification of reactive oxygen species is accompanied by production of glutathione oxidized. Glutathione oxidized can be used for the research of sickle cells and erythrocytes[1][2]. Glutathione oxidized (GSSG) is produced by the oxidation of glutathione. Detoxification of reactive oxygen species is accompanied by production of glutathione oxidized. Glutathione oxidized can be used for the research of sickle cells and erythrocytes[1].

D-Allothreonine

C4H9NO3 (119.0582404)

The D-enantiomer of allothreonine. It occurs as a component of peptido-lipids in certain bacteria. D-Allothreonine is the D type stereoisomer of Allothreonine. D-Allothreonine is a peptido-lipid derived from bacteria. D-Allothreonine, amide-linked to the D-galacturonic acid, is also a constituent in the polysaccharide[1][2].

2-aminobutyrate

C4H9NO2 (103.0633254)