Reaction Process: Plant Reactome:R-TUR-1119365
Lysine degradation II related metabolites
find 15 related metabolites which is associated with chemical reaction(pathway) Lysine degradation II
H2O + NAD + allysine ⟶ NADH + alpha-aminoadipate
Oxoglutaric acid
Oxoglutaric acid, also known as alpha-ketoglutarate, alpha-ketoglutaric acid, AKG, or 2-oxoglutaric acid, is classified as a gamma-keto acid or a gamma-keto acid derivative. gamma-Keto acids are organic compounds containing an aldehyde substituted with a keto group on the C4 carbon atom. alpha-Ketoglutarate is considered to be soluble (in water) and acidic. alpha-Ketoglutarate is a key molecule in the TCA cycle, playing a fundamental role in determining the overall rate of this important metabolic process (PMID: 26759695). In the TCA cycle, AKG is decarboxylated to succinyl-CoA and carbon dioxide by AKG dehydrogenase, which functions as a key control point of the TCA cycle. Additionally, AKG can be generated from isocitrate by oxidative decarboxylation catalyzed by the enzyme known as isocitrate dehydrogenase (IDH). In addition to these routes of production, AKG can be produced from glutamate by oxidative deamination via glutamate dehydrogenase, and as a product of pyridoxal phosphate-dependent transamination reactions (mediated by branched-chain amino acid transaminases) in which glutamate is a common amino donor. AKG is a nitrogen scavenger and a source of glutamate and glutamine that stimulates protein synthesis and inhibits protein degradation in muscles. In particular, AKG can decrease protein catabolism and increase protein synthesis to enhance bone tissue formation in skeletal muscles (PMID: 26759695). Interestingly, enteric feeding of AKG supplements can significantly increase circulating plasma levels of hormones such as insulin, growth hormone, and insulin-like growth factor-1 (PMID: 26759695). It has recently been shown that AKG can extend the lifespan of adult C. elegans by inhibiting ATP synthase and TOR (PMID: 24828042). In combination with molecular oxygen, alpha-ketoglutarate is required for the hydroxylation of proline to hydroxyproline in the production of type I collagen. A recent study has shown that alpha-ketoglutarate promotes TH1 differentiation along with the depletion of glutamine thereby favouring Treg (regulatory T-cell) differentiation (PMID: 26420908). alpha-Ketoglutarate has been found to be associated with fumarase deficiency, 2-ketoglutarate dehydrogenase complex deficiency, and D-2-hydroxyglutaric aciduria, which are all inborn errors of metabolism (PMID: 8338207). Oxoglutaric acid has been found to be a metabolite produced by Corynebacterium and yeast (PMID: 27872963) (YMDB). [Spectral] 2-Oxoglutarate (exact mass = 146.02152) and S-Adenosyl-L-homocysteine (exact mass = 384.12159) were not completely separated on HPLC under the present analytical conditions as described in AC$XXX. Additionally some of the peaks in this data contains dimers and other unidentified ions. [Spectral] 2-Oxoglutarate (exact mass = 146.02152) and (S)-Malate (exact mass = 134.02152) were not completely separated on HPLC under the present analytical conditions as described in AC$XXX. Additionally some of the peaks in this data contains dimers and other unidentified ions. Flavouring ingredient
Aminoadipic acid
Aminoadipic acid (CAS: 542-32-5), also known as 2-aminoadipate, is a metabolite in the principal biochemical pathway of lysine. It is an intermediate in the metabolism (i.e. breakdown or degradation) of lysine and saccharopine. It antagonizes neuroexcitatory activity modulated by the glutamate receptor N-methyl-D-aspartate (NMDA). Aminoadipic acid has also been shown to inhibit the production of kynurenic acid, a broad spectrum excitatory amino acid receptor antagonist, in brain tissue slices (PMID: 8566117). Recent studies have shown that aminoadipic acid is elevated in prostate biopsy tissues from prostate cancer patients (PMID: 23737455). Mutations in DHTKD1 (dehydrogenase E1 and transketolase domain-containing protein 1) have been shown to cause human 2-aminoadipic aciduria and 2-oxoadipic aciduria via impaired decarboxylation of 2-oxoadipate to glutaryl-CoA, which is the last step in the lysine degradation pathway (PMID: 23141293). Aging, diabetes, sepsis, and renal failure are known to catalyze the oxidation of lysyl residues to form 2-aminoadipic acid in human skin collagen and potentially other tissues (PMID: 18448817). Proteolytic breakdown of these tissues can lead to the release of free 2-aminoadipic acid. Studies in rats indicate that aminoadipic acid (along with the three branched-chain amino acids: leucine, valine, and isoleucine) levels are elevated in the pre-diabetic phase and so aminoadipic acid may serve as a predictive biomarker for the development of diabetes (PMID: 15389298). Long-term hyperglycemia of endothelial cells can also lead to elevated levels of aminoadipate which is thought to be a sign of lysine breakdown through oxidative stress and reactive oxygen species (ROS) (PMID: 21961526). 2-Aminoadipate is a potential small-molecule marker of oxidative stress (PMID: 21647514). Therefore, depending on the circumstances aminoadipic acid can act as an acidogen, a diabetogen, an atherogen, and a metabotoxin. An acidogen is an acidic compound that induces acidosis, which has multiple adverse effects on many organ systems. A diabetogen is a compound that can lead to type 2 diabetes. An atherogen is a compound that leads to atherosclerosis and cardiovascular disease. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of aminoadipic acid are associated with at least two inborn errors of metabolism including 2-aminoadipic aciduria and 2-oxoadipic aciduria. Aminoadipic acid is an organic acid and 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 abnormalities, kidney abnormalities, liver damage, 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. As a diabetogen, serum aminoadipic levels appear to regulate glucose homeostasis and have been highly predictive of individuals who later develop diabetes (PMID: 24091325). In particular, aminoadipic acid lowers fasting plasma glucose levels and enhances insulin secretion from human islets. As an atherogen, aminoadipic acid has been found to be produced at high levels via protein lysine oxidation in atherosclerotic plaques (PMID: 28069522). A metabolite in the principal biochemical pathway of lysine. It antagonizes neuroexcitatory activity modulated by the glutamate receptor, N-methyl-D-aspartate; (NMDA). L-α-Aminoadipic acid. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=1118-90-7 (retrieved 2024-07-01) (CAS RN: 1118-90-7). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). Aminoadipic acid is an intermediate in the metabolism of lysine and saccharopine. Aminoadipic acid is an intermediate in the metabolism of lysine and saccharopine.
Saccharopine
Saccharopine is an intermediate in the degradation of lysine, formed by the condensation of lysine and alpha-ketoglutarate. The saccharopine pathway is the main route for lysine degradation in mammals, and its first two reactions are catalyzed by enzymatic activities known as lysine-oxoglutarate reductase (LOR) and saccharopine dehydrogenase (SDH), which reside on a single bifunctional polypeptide (LOR/SDH) (EC 1.5.1.8). The reactions involved with saccharopine dehydrogenases have very strict substrate specificity for L-lysine, 2-oxoglutarate, and NADPH. LOR/SDH has been detected in a number of mammalian tissues, mainly in the liver and kidney, contributing not only to the general nitrogen balance in the organism but also to the controlled conversion of lysine into ketone bodies. A tetrameric form has also been observed in human liver and placenta. LOR activity has also been detected in brain mitochondria during embryonic development, and this opens up the question of whether or not lysine degradation has any functional significance during brain development. As a result, there is now a new focus on the nutritional requirements for lysine in gestation and infancy. Finally, LOR and/or SDH deficiencies seem to be involved in a human autosomal genetic disorder known as familial hyperlysinemia, which is characterized by serious defects in the functioning of the nervous system and characterized by a deficiency in lysine-ketoglutarate reductase, saccharopine dehydrogenase, and saccharopine oxidoreductase activities. Saccharopinuria (high amounts of saccharopine in the urine) and saccharopinemia (an excess of saccharopine in the blood) are conditions present in some inherited disorders of lysine degradation (PMID: 463877, 10567240, 10772957, 4809305). If present in sufficiently high levels, saccharopine 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. Saccharopine 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). Many affected children with organic acidemias experience intellectual disability or delayed development. Amino acid from Saccharomyces cerevisiae and Neurospora crassaand is also found in mushrooms and seeds
Nicotinamide adenine dinucleotide phosphate
NADPH is the reduced form of NADP+, and NADP+ is the oxidized form of NADPH. Nicotinamide adenine dinucleotide phosphate (NADP) is a coenzyme composed of ribosylnicotinamide 5-phosphate (NMN) coupled with a pyrophosphate linkage to 5-phosphate adenosine 2,5-bisphosphate. NADP serves as an electron carrier in a number of reactions, being alternately oxidized (NADP+) and reduced (NADPH). NADP is formed through the addition of a phosphate group to the 2 position of the adenosyl nucleotide through an ester linkage (Dorland, 27th ed). This extra phosphate is added by the enzyme NAD+ kinase and removed via NADP+ phosphatase. NADP is also known as TPN (triphosphopyridine nucleotide) and it is an important cofactor used in anabolic reactions in all forms of cellular life. Examples include the Calvin cycle, cholesterol synthesis, fatty acid elongation, and nucleic acid synthesis (Wikipedia). Nicotinamide adenine dinucleotide phosphate. A coenzyme composed of ribosylnicotinamide 5-phosphate (NMN) coupled by pyrophosphate linkage to the 5-phosphate adenosine 2,5-bisphosphate. It serves as an electron carrier in a number of reactions, being alternately oxidized (NADP+) and reduced (NADPH). (Dorland, 27th ed.) [HMDB]. NADPH is found in many foods, some of which are american pokeweed, rice, ginseng, and ostrich fern. COVID info from COVID-19 Disease Map Corona-virus Coronavirus SARS-CoV-2 COVID-19 SARS-CoV COVID19 SARS2 SARS
Lipoamide
C8H15NOS2 (205.05950199999998)
Lipoamide is a trivial name for 6,8-dithiooctanoic amide. It is 6,8-dithiooctanoic acids functional form where the carboxyl group is attached to protein (or any other amine) by an amide linkage (containing -NH2) to an amino group. Lipoamide forms a thioester bond, oxidizing the disulfide bond, with acetaldehyde (pyruvate after it has been decarboxylated). It then transfers the acetaldehyde group to CoA which can then continue in the TCA cycle. Lipoamide is an intermediate in glycolysis/gluconeogenesis, citrate cycle (TCA cycle), alanine, aspartate and pyruvate metabolism, and valine, leucine and isoleucine degradation (KEGG:C00248). It is generated from dihydrolipoamide via the enzyme dihydrolipoamide dehydrogenase (EC:1.8.1.4) and then converted to S-glutaryl-dihydrolipoamide via the enzyme oxoglutarate dehydrogenase (EC:1.2.4.2). Lipoamide is the oxidized form of glutathione. (PMID:8957191) KEIO_ID L031; [MS2] KO009031 KEIO_ID L031
Nadide
[C21H28N7O14P2]+ (664.1169428000001)
[Spectral] NAD+ (exact mass = 663.10912) and 3,4-Dihydroxy-L-phenylalanine (exact mass = 197.06881) and Cytidine (exact mass = 243.08552) were not completely separated on HPLC under the present analytical conditions as described in AC$XXX. Additionally some of the peaks in this data contains dimers and other unidentified ions. [Spectral] NAD+ (exact mass = 663.10912) and NADP+ (exact mass = 743.07545) were not completely separated on HPLC under the present analytical conditions as described in AC$XXX. Additionally some of the peaks in this data contains dimers and other unidentified ions. COVID info from COVID-19 Disease Map Corona-virus Coronavirus SARS-CoV-2 COVID-19 SARS-CoV COVID19 SARS2 SARS
2-Oxoadipic acid
2-Oxoadipic acid is produced from lysine in the cytosol of cells via the saccharopine and the pipecolic acid pathways. Catabolites of hydroxylysine and tryptophan enter these pathways as 2-aminoadipic- -semialdehyde and 2-oxoadipate, respectively. In the matrix of mitochondria, 2-oxoadipate is decarboxylated to glutaryl-CoA by the 2-oxoadipate dehydrogenase complex and then converted to acetyl-CoA. 2-Oxoadipic aciduria is an in-born error of metabolism of lysine, tryptophan, and hydroxylysine, in which abnormal quantities of 2-aminoadipic acid are found in body fluids along with 2-oxoadipic acid. Patients with 2-Oxoadipic acidemias are mentally retarded with hypotonia or seizures. 2-Oxoadipic aciduria can occur in patients with Kearns-Sayre Syndrome, a progressive disorder with onset prior to 20 years of age in which multiple organ systems are affected, including progressive external ophthalmoplegia, retinopathy, and the age of onset, and these are associated classically with abnormalities in cardiac conduction, cerebellar signs, and elevated cerebrospinal fluid protein (PMID: 10655159, 16183823, 11083877). Oxoadipic acid is found to be associated with alpha-aminoadipic aciduria, which is an inborn error of metabolism. Present in pea seedlings KEIO_ID K009 Oxoadipic acid is a key metabolite of the essential amino acids tryptophan and lysine.
NADP+
[C21H29N7O17P3]+ (744.0832754)
[Spectral] NADP+ (exact mass = 743.07545) and NAD+ (exact mass = 663.10912) 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. COVID info from COVID-19 Disease Map Corona-virus Coronavirus SARS-CoV-2 COVID-19 SARS-CoV COVID19 SARS2 SARS
1,4-Dihydronicotinamide adenine dinucleotide
Nicotinamide adenine dinucleotide (NAD) is a coenzyme central to metabolism. Found in all living cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an adenine nucleobase and the other nicotinamide. NAD exists in two forms: an oxidized and reduced form, abbreviated as NAD+ and NADH (H for hydrogen) respectively. NADH is the reduced form of NAD+, and NAD+ is the oxidized form of NADH. NAD (or nicotinamide adenine dinucleotide) is used extensively in glycolysis and the citric acid cycle of cellular respiration. The reducing potential stored in NADH can be either converted into ATP through the electron transport chain or used for anabolic metabolism. ATP "energy" is necessary for an organism to live. Green plants obtain ATP through photosynthesis, while other organisms obtain it via cellular respiration. NAD is a coenzyme composed of ribosylnicotinamide 5-diphosphate coupled to adenosine 5-phosphate by a pyrophosphate linkage. It is found widely in nature and is involved in numerous enzymatic reactions in which it serves as an electron carrier by being alternately oxidized (NAD+) and reduced (NADH). NADP is formed through the addition of a phosphate group to the 2 position of the adenosyl nucleotide through an ester linkage. NADH is the reduced form of NAD+, and NAD+ is the oxidized form of NADH, A coenzyme composed of ribosylnicotinamide 5-diphosphate coupled to adenosine 5-phosphate by pyrophosphate linkage. It is found widely in nature and is involved in numerous enzymatic reactions in which it serves as an electron carrier by being alternately oxidized (NAD+) and reduced (NADH). It forms NADP with the addition of a phosphate group to the 2 position of the adenosyl nucleotide through an ester linkage.(Dorland, 27th ed) [HMDB]. NADH is found in many foods, some of which are dill, ohelo berry, fox grape, and black-eyed pea. Acquisition and generation of the data is financially supported in part by CREST/JST. COVID info from COVID-19 Disease Map Corona-virus Coronavirus SARS-CoV-2 COVID-19 SARS-CoV COVID19 SARS2 SARS
Allysine
Allysine (CAS: 1962-83-0), also known as 2-amino-6-oxohexanoic acid or 6-oxonorleucine, 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). Outside of the human body, allysine has been detected, but not quantified in, several different foods, such as winged beans, wasabi, common verbena, arrowhead, and oats. This could make allysine a potential biomarker for the consumption of these foods. Allysine is a derivative of lysine used in the production of elastin and collagen. It is produced by the actions of the enzyme lysyl oxidase in the extracellular matrix and is essential in the crosslink formation that stabilizes collagen and elastin.
Water
Water is a chemical substance that is essential to all known forms of life. It appears colorless to the naked eye in small quantities, though it is actually slightly blue in color. It covers 71\\% of Earths surface. Current estimates suggest that there are 1.4 billion cubic kilometers (330 million m3) of it available on Earth, and it exists in many forms. It appears mostly in the oceans (saltwater) and polar ice caps, but it is also present as clouds, rain water, rivers, freshwater aquifers, lakes, and sea ice. Water in these bodies perpetually moves through a cycle of evaporation, precipitation, and runoff to the sea. Clean water is essential to human life. In many parts of the world, it is in short supply. From a biological standpoint, water has many distinct properties that are critical for the proliferation of life that set it apart from other substances. It carries out this role by allowing organic compounds to react in ways that ultimately allow replication. All known forms of life depend on water. Water is vital both as a solvent in which many of the bodys solutes dissolve and as an essential part of many metabolic processes within the body. Metabolism is the sum total of anabolism and catabolism. In anabolism, water is removed from molecules (through energy requiring enzymatic chemical reactions) in order to grow larger molecules (e.g. starches, triglycerides and proteins for storage of fuels and information). In catabolism, water is used to break bonds in order to generate smaller molecules (e.g. glucose, fatty acids and amino acids to be used for fuels for energy use or other purposes). Water is thus essential and central to these metabolic processes. Water is also central to photosynthesis and respiration. Photosynthetic cells use the suns energy to split off waters hydrogen from oxygen. Hydrogen is combined with CO2 (absorbed from air or water) to form glucose and release oxygen. All living cells use such fuels and oxidize the hydrogen and carbon to capture the suns energy and reform water and CO2 in the process (cellular respiration). Water is also central to acid-base neutrality and enzyme function. An acid, a hydrogen ion (H+, that is, a proton) donor, can be neutralized by a base, a proton acceptor such as hydroxide ion (OH-) to form water. Water is considered to be neutral, with a pH (the negative log of the hydrogen ion concentration) of 7. Acids have pH values less than 7 while bases have values greater than 7. Stomach acid (HCl) is useful to digestion. However, its corrosive effect on the esophagus during reflux can temporarily be neutralized by ingestion of a base such as aluminum hydroxide to produce the neutral molecules water and the salt aluminum chloride. Human biochemistry that involves enzymes usually performs optimally around a biologically neutral pH of 7.4. (Wikipedia). Water, also known as purified water or dihydrogen oxide, is a member of the class of compounds known as homogeneous other non-metal compounds. Homogeneous other non-metal compounds are inorganic non-metallic compounds in which the largest atom belongs to the class of other nonmetals. Water can be found in a number of food items such as caraway, oxheart cabbage, alaska wild rhubarb, and japanese walnut, which makes water a potential biomarker for the consumption of these food products. Water can be found primarily in most biofluids, including ascites Fluid, blood, cerebrospinal fluid (CSF), and lymph, as well as throughout all human tissues. Water exists in all living species, ranging from bacteria to humans. In humans, water is involved in several metabolic pathways, some of which include cardiolipin biosynthesis CL(20:4(5Z,8Z,11Z,14Z)/18:0/20:4(5Z,8Z,11Z,14Z)/18:2(9Z,12Z)), cardiolipin biosynthesis cl(i-13:0/i-15:0/i-20:0/i-24:0), cardiolipin biosynthesis CL(18:0/18:0/20:4(5Z,8Z,11Z,14Z)/22:5(7Z,10Z,13Z,16Z,19Z)), and cardiolipin biosynthesis cl(a-13:0/i-18:0/i-13:0/i-19:0). Water is also involved in several metabolic disorders, some of which include de novo triacylglycerol biosynthesis tg(i-21:0/i-13:0/21:0), de novo triacylglycerol biosynthesis tg(22:0/20:0/i-20:0), de novo triacylglycerol biosynthesis tg(a-21:0/i-20:0/i-14:0), and de novo triacylglycerol biosynthesis tg(i-21:0/a-17:0/i-12:0). Water is a drug which is used for diluting or dissolving drugs for intravenous, intramuscular or subcutaneous injection, according to instructions of the manufacturer of the drug to be administered [fda label]. Water plays an important role in the world economy. Approximately 70\\% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a major source of food for many parts of the world. Much of long-distance trade of commodities (such as oil and natural gas) and manufactured products is transported by boats through seas, rivers, lakes, and canals. Large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a wide variety of chemical substances; as such it is widely used in industrial processes, and in cooking and washing. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, and diving .
Carbon dioxide
Carbon dioxide is a colorless, odorless gas that can be formed by the body and is necessary for the respiration cycle of plants and animals. Carbon dioxide is produced during respiration by all animals, fungi and microorganisms that depend on living and decaying plants for food, either directly or indirectly. It is, therefore, a major component of the carbon cycle. Additionally, carbon dioxide is used by plants during photosynthesis to make sugars which may either be consumed again in respiration or used as the raw material to produce polysaccharides such as starch and cellulose, proteins and the wide variety of other organic compounds required for plant growth and development. When inhaled at concentrations much higher than usual atmospheric levels, it can produce a sour taste in the mouth and a stinging sensation in the nose and throat. These effects result from the gas dissolving in the mucous membranes and saliva, forming a weak solution of carbonic acid. Carbon dioxide is used by the food industry, the oil industry, and the chemical industry. Carbon dioxide is used to produce carbonated soft drinks and soda water. Traditionally, the carbonation in beer and sparkling wine comes about through natural fermentation, but some manufacturers carbonate these drinks artificially. Leavening agent, propellant, aerating agent, preservative. Solvent for supercritical extraction e.g. of caffeine in manufacture of caffeine-free instant coffee. It is used in carbonation of beverages, in the frozen food industry and as a component of controlled atmosphere packaging (CAD) to inhibit bacterial growth. Especies effective against Gram-negative spoilage bacteria, e.g. Pseudomonas V - Various > V03 - All other therapeutic products > V03A - All other therapeutic products > V03AN - Medical gases
S-Glutaryldihydrolipoamide
S-Glutaryldihydrolipoamide is involved in the lysine degradation pathway. S-Glutaryldihydrolipoamide can be irreversibly created from 2-Oxoadipate by 2-oxoglutarate dehydrogenase E1 component [EC:1.2.4.2]. S-Glutaryldihydrolipoamide can be reversibly created from Glutaryl-CoA by 2-oxoglutarate dehydrogenase E2 component (dihydrolipoamide. succinyltransferase) [EC:2.3.1.61]. S-Glutaryldihydrolipoamide is involved in the lysine degradation pathway. S-Glutaryldihydrolipoamide can be irreversibly created from 2-Oxoadipate by 2-oxoglutarate dehydrogenase E1 component [EC:1.2.4.2]. S-Glutaryldihydrolipoamide can be reversibly created from Glutaryl-CoA by 2-oxoglutarate dehydrogenase E2 component (dihydrolipoamide
L-glutamate(1-)
An alpha-amino-acid anion that is the conjugate base of L-glutamic acid, having anionic carboxy groups and a cationic amino group