Reaction Process: WikiPathways:WP78

TCA cycle (aka Krebs or citric acid cycle) related metabolites

find 9 related metabolites which is associated with chemical reaction(pathway) TCA cycle (aka Krebs or citric acid cycle)

cis-aconitate ⟶ citrate

Citric acid

2-hydroxypropane-1,2,3-tricarboxylic acid

C6H8O7 (192.027)


Citric acid (citrate) is a tricarboxylic acid, an organic acid with three carboxylate groups. Citrate is an intermediate in the TCA cycle (also known as the Tricarboxylic Acid cycle, the Citric Acid cycle or Krebs cycle). The TCA cycle is a central metabolic pathway for all animals, plants, and bacteria. As a result, citrate is found in all living organisms, from bacteria to plants to animals. In the TCA cycle, the enzyme citrate synthase catalyzes the condensation of oxaloacetate with acetyl CoA to form citrate. Citrate then acts as the substrate for the enzyme known as aconitase and is then converted into aconitic acid. The TCA cycle ends with regeneration of oxaloacetate. This series of chemical reactions in the TCA cycle is the source of two-thirds of the food-derived energy in higher organisms. Citrate can be transported out of the mitochondria and into the cytoplasm, then broken down into acetyl-CoA for fatty acid synthesis, and into oxaloacetate. Citrate is a positive modulator of this conversion, and allosterically regulates the enzyme acetyl-CoA carboxylase, which is the regulating enzyme in the conversion of acetyl-CoA into malonyl-CoA (the commitment step in fatty acid synthesis). In short, citrate is transported into the cytoplasm, converted into acetyl CoA, which is then converted into malonyl CoA by acetyl CoA carboxylase, which is allosterically modulated by citrate. In mammals and other vertebrates, Citrate is a vital component of bone, helping to regulate the size of apatite crystals (PMID: 21127269). Citric acid is found in citrus fruits, most concentrated in lemons and limes, where it can comprise as much as 8\\\\\% of the dry weight of the fruit. Citric acid is a natural preservative and is also used to add an acidic (sour) taste to foods and carbonated drinks. Because it is one of the stronger edible acids, the dominant use of citric acid is as a flavoring and preservative in food and beverages, especially soft drinks and candies. Citric acid is an excellent chelating agent, binding metals by making them soluble. It is used to remove and discourage the buildup of limescale from boilers and evaporators. It can be used to treat water, which makes it useful in improving the effectiveness of soaps and laundry detergents. The salts of citric acid (citrates) can be used as anticoagulants due to their calcium chelating ability. Intolerance to citric acid in the diet is known to exist. Little information is available as the condition appears to be rare, but like other types of food intolerance it is often described as a "pseudo-allergic" reaction. Citric acid appears as colorless, odorless crystals with an acid taste. Denser than water. (USCG, 1999) Citric acid is a tricarboxylic acid that is propane-1,2,3-tricarboxylic acid bearing a hydroxy substituent at position 2. It is an important metabolite in the pathway of all aerobic organisms. It has a role as a food acidity regulator, a chelator, an antimicrobial agent and a fundamental metabolite. It is a conjugate acid of a citrate(1-) and a citrate anion. A key intermediate in metabolism. It is an acid compound found in citrus fruits. The salts of citric acid (citrates) can be used as anticoagulants due to their calcium-chelating ability. Citric acid is one of the active ingredients in Phexxi, a non-hormonal contraceptive agent that was approved by the FDA on May 2020. It is also used in combination with magnesium oxide to form magnesium citrate, an osmotic laxative. Citric acid is a metabolite found in or produced by Escherichia coli (strain K12, MG1655). Anhydrous citric acid is a Calculi Dissolution Agent and Anti-coagulant. The mechanism of action of anhydrous citric acid is as an Acidifying Activity and Calcium Chelating Activity. The physiologic effect of anhydrous citric acid is by means of Decreased Coagulation Factor Activity. Anhydrous Citric Acid is a tricarboxylic acid found in citrus fruits. Citric acid is used as an excipient in pharmaceutical preparations due to its antioxidant properties. It maintains stability of active ingredients and is used as a preservative. It is also used as an acidulant to control pH and acts as an anticoagulant by chelating calcium in blood. A key intermediate in metabolism. It is an acid compound found in citrus fruits. The salts of citric acid (citrates) can be used as anticoagulants due to their calcium chelating ability. See also: Citric Acid Monohydrate (related). Citrate, also known as anhydrous citric acid or 2-hydroxy-1,2,3-propanetricarboxylic acid, belongs to tricarboxylic acids and derivatives class of compounds. Those are carboxylic acids containing exactly three carboxyl groups. Citrate is soluble (in water) and a weakly acidic compound (based on its pKa). Citrate can be found in a number of food items such as ucuhuba, loquat, bayberry, and longan, which makes citrate a potential biomarker for the consumption of these food products. Citrate can be found primarily in most biofluids, including saliva, sweat, feces, and blood, as well as throughout all human tissues. Citrate exists in all living species, ranging from bacteria to humans. In humans, citrate is involved in several metabolic pathways, some of which include the oncogenic action of succinate, the oncogenic action of fumarate, the oncogenic action of 2-hydroxyglutarate, and congenital lactic acidosis. Citrate is also involved in several metabolic disorders, some of which include 2-ketoglutarate dehydrogenase complex deficiency, pyruvate dehydrogenase deficiency (E2), fumarase deficiency, and glutaminolysis and cancer. Moreover, citrate is found to be associated with lung Cancer, tyrosinemia I, maple syrup urine disease, and propionic acidemia. A citrate is a derivative of citric acid; that is, the salts, esters, and the polyatomic anion found in solution. An example of the former, a salt is trisodium citrate; an ester is triethyl citrate. When part of a salt, the formula of the citrate ion is written as C6H5O73− or C3H5O(COO)33− . A tricarboxylic acid that is propane-1,2,3-tricarboxylic acid bearing a hydroxy substituent at position 2. It is an important metabolite in the pathway of all aerobic organisms. Citric acid. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=77-92-9 (retrieved 2024-07-01) (CAS RN: 77-92-9). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). Citric acid is a natural preservative and food tartness enhancer. Citric acid induces apoptosis and cell cycle arrest at G2/M phase and S phase in HaCaT cells. Citric acid cause oxidative damage of the liver by means of the decrease of antioxidative enzyme activities. Citric acid causes renal toxicity in mice[1][2][3]. Citric acid is a natural preservative and food tartness enhancer. Citric acid induces apoptosis and cell cycle arrest at G2/M phase and S phase in HaCaT cells. Citric acid cause oxidative damage of the liver by means of the decrease of antioxidative enzyme activities. Citric acid causes renal toxicity in mice[1][2][3].

   

Fumaric acid

(2E)-but-2-enedioic acid

C4H4O4 (116.011)


Fumaric acid appears as a colorless crystalline solid. The primary hazard is the threat to the environment. Immediate steps should be taken to limit spread to the environment. Combustible, though may be difficult to ignite. Used to make paints and plastics, in food processing and preservation, and for other uses. Fumaric acid is a butenedioic acid in which the C=C double bond has E geometry. It is an intermediate metabolite in the citric acid cycle. It has a role as a food acidity regulator, a fundamental metabolite and a geroprotector. It is a conjugate acid of a fumarate(1-). Fumaric acid is a metabolite found in or produced by Escherichia coli (strain K12, MG1655). Fumaric acid is a precursor to L-malate in the Krebs tricarboxylic acid cycle. It is formed by the oxidation of succinate by succinate dehydrogenase. Fumarate is converted by fumarase to malate. A fumarate is a salt or ester of the organic compound fumaric acid, a dicarboxylic acid. Fumarate has recently been recognized as an oncometabolite. (A15199). As a food additive, fumaric acid is used to impart a tart taste to processed foods. It is also used as an antifungal agent in boxed foods such as cake mixes and flours, as well as tortillas. Fumaric acid is also added to bread to increase the porosity of the final baked product. It is used to impart a sour taste to sourdough and rye bread. In cake mixes, it is used to maintain a low pH and prevent clumping of the flours used in the mix. In fruit drinks, fumaric acid is used to maintain a low pH which, in turn, helps to stabilize flavor and color. Fumaric acid also prevents the growth of E. coli in beverages when used in combination with sodium benzoate. When added to wines, fumaric acid helps to prevent further fermentation and yet maintain low pH and eliminate traces of metallic elements. In this fashion, it helps to stabilize the taste of wine. Fumaric acid can also be added to dairy products, sports drinks, jams, jellies and candies. Fumaric acid helps to break down bonds between gluten proteins in wheat and helps to create a more pliable dough. Fumaric acid is used in paper sizing, printer toner, and polyester resin for making molded walls. Fumaric acid is a dicarboxylic acid. It is a precursor to L-malate in the Krebs tricarboxylic acid (TCA) cycle. It is formed by the oxidation of succinic acid by succinate dehydrogenase. Fumarate is converted by the enzyme fumarase to malate. Fumaric acid has recently been identified as an oncometabolite or an endogenous, cancer causing metabolite. High levels of this organic acid can be found in tumors or biofluids surrounding tumors. Its oncogenic action appears to due to its ability to inhibit prolyl hydroxylase-containing enzymes. In many tumours, oxygen availability becomes limited (hypoxia) very quickly due to rapid cell proliferation and limited blood vessel growth. The major regulator of the response to hypoxia is the HIF transcription factor (HIF-alpha). Under normal oxygen levels, protein levels of HIF-alpha are very low due to constant degradation, mediated by a series of post-translational modification events catalyzed by the prolyl hydroxylase domain-containing enzymes PHD1, 2 and 3, (also known as EglN2, 1 and 3) that hydroxylate HIF-alpha and lead to its degradation. All three of the PHD enzymes are inhibited by fumarate. Fumaric acid is found to be associated with fumarase deficiency, which is an inborn error of metabolism. It is also a metabolite of Aspergillus. Produced industrially by fermentation of Rhizopus nigricans, or manufactured by catalytic or thermal isomerisation of maleic anhydride or maleic acid. Used as an antioxidant, acidulant, leavening agent and flavouring agent in foods. Present in raw lean fish. Dietary supplement. Used in powdered products since fumaric acid is less hygroscopic than other acids. A precursor to L-malate in the Krebs tricarboxylic acid cycle. It is formed by the oxidation of succinate by succinate dehydrogenase (wikipedia). Fumaric acid is also found in garden tomato, papaya, wild celery, and star fruit. Fumaric acid. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=110-17-8 (retrieved 2024-07-01) (CAS RN: 110-17-8). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). Fumaric acid, associated with fumarase deficiency, is identified as an oncometabolite or an endogenous, cancer causing metabolite. Fumaric acid, associated with fumarase deficiency, is identified as an oncometabolite or an endogenous, cancer causing metabolite.

   

Succinic acid

butanedioic acid

C4H6O4 (118.0266)


Succinic acid appears as white crystals or shiny white odorless crystalline powder. pH of 0.1 molar solution: 2.7. Very acid taste. (NTP, 1992) Succinic acid is an alpha,omega-dicarboxylic acid resulting from the formal oxidation of each of the terminal methyl groups of butane to the corresponding carboxy group. It is an intermediate metabolite in the citric acid cycle. It has a role as a nutraceutical, a radiation protective agent, an anti-ulcer drug, a micronutrient and a fundamental metabolite. It is an alpha,omega-dicarboxylic acid and a C4-dicarboxylic acid. It is a conjugate acid of a succinate(1-). A water-soluble, colorless crystal with an acid taste that is used as a chemical intermediate, in medicine, the manufacture of lacquers, and to make perfume esters. It is also used in foods as a sequestrant, buffer, and a neutralizing agent. (Hawleys Condensed Chemical Dictionary, 12th ed, p1099; McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1851) Succinic acid is a metabolite found in or produced by Escherichia coli (strain K12, MG1655). Succinic acid is a dicarboxylic acid. The anion, succinate, is a component of the citric acid cycle capable of donating electrons to the electron transfer chain. Succinic acid is created as a byproduct of the fermentation of sugar. It lends to fermented beverages such as wine and beer a common taste that is a combination of saltiness, bitterness and acidity. Succinate is commonly used as a chemical intermediate, in medicine, the manufacture of lacquers, and to make perfume esters. It is also used in foods as a sequestrant, buffer, and a neutralizing agent. Succinate plays a role in the citric acid cycle, an energy-yielding process and is metabolized by succinate dehydrogenase to fumarate. Succinate dehydrogenase (SDH) plays an important role in the mitochondria, being both part of the respiratory chain and the Krebs cycle. SDH with a covalently attached FAD prosthetic group, binds enzyme substrates (succinate and fumarate) and physiological regulators (oxaloacetate and ATP). Oxidizing succinate links SDH to the fast-cycling Krebs cycle portion where it participates in the breakdown of acetyl-CoA throughout the whole Krebs cycle. Succinate can readily be imported into the mitochondrial matrix by the n-butylmalonate- (or phenylsuccinate-) sensitive dicarboxylate carrier in exchange with inorganic phosphate or another organic acid, e.g. malate. (A3509) Mutations in the four genes encoding the subunits of succinate dehydrogenase are associated with a wide spectrum of clinical presentations (i.e.: Huntingtons disease. (A3510). Succinate also acts as an oncometabolite. Succinate inhibits 2-oxoglutarate-dependent histone and DNA demethylase enzymes, resulting in epigenetic silencing that affects neuroendocrine differentiation. A water-soluble, colorless crystal with an acid taste that is used as a chemical intermediate, in medicine, the manufacture of lacquers, and to make perfume esters. It is also used in foods as a sequestrant, buffer, and a neutralizing agent. (Hawleys Condensed Chemical Dictionary, 12th ed, p1099; McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1851) Succinic acid (succinate) is a dicarboxylic acid. It is an important component of the citric acid or TCA cycle and is capable of donating electrons to the electron transfer chain. Succinate is found in all living organisms ranging from bacteria to plants to mammals. In eukaryotes, succinate is generated in the mitochondria via the tricarboxylic acid cycle (TCA). Succinate can readily be imported into the mitochondrial matrix by the n-butylmalonate- (or phenylsuccinate-) sensitive dicarboxylate carrier in exchange with inorganic phosphate or another organic acid, e. g. malate (PMID 16143825). Succinate can exit the mitochondrial matrix and function in the cytoplasm as well as the extracellular space. Succinate has multiple biological roles including roles as a metabolic intermediate and roles as a cell signalling molecule. Succinate can alter gene expression patterns, thereby modulating the epigenetic landscape or it can exhibit hormone-like signaling functions (PMID: 26971832). As such, succinate links cellular metabolism, especially ATP formation, to the regulation of cellular function. Succinate can be broken down or metabolized into fumarate by the enzyme succinate dehydrogenase (SDH), which is part of the electron transport chain involved in making ATP. Dysregulation of succinate synthesis, and therefore ATP synthesis, can happen in a number of genetic mitochondrial diseases, such as Leigh syndrome, and Melas syndrome. Succinate has been found to be associated with D-2-hydroxyglutaric aciduria, which is an inborn error of metabolism. Succinic acid has recently been identified as an oncometabolite or an endogenous, cancer causing metabolite. High levels of this organic acid can be found in tumors or biofluids surrounding tumors. Its oncogenic action appears to due to its ability to inhibit prolyl hydroxylase-containing enzymes. In many tumours, oxygen availability becomes limited (hypoxia) very quickly due to rapid cell proliferation and limited blood vessel growth. The major regulator of the response to hypoxia is the HIF transcription factor (HIF-alpha). Under normal oxygen levels, protein levels of HIF-alpha are very low due to constant degradation, mediated by a series of post-translational modification events catalyzed by the prolyl hydroxylase domain-containing enzymes PHD1, 2 and 3, (also known as EglN2, 1 and 3) that hydroxylate HIF-alpha and lead to its degradation. All three of the PHD enzymes are inhibited by succinate. In humans, urinary succinic acid is produced by Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, Enterobacter, Acinetobacter, Proteus mirabilis, Citrobacter frundii, Enterococcus faecalis (PMID: 22292465). Succinic acid is also found in Actinobacillus, Anaerobiospirillum, Mannheimia, Corynebacterium and Basfia (PMID: 22292465; PMID: 18191255; PMID: 26360870). Succinic acid is widely distributed in higher plants and produced by microorganisms. It is found in cheeses and fresh meats. Succinic acid is a flavouring enhancer, pH control agent [DFC]. Succinic acid is also found in yellow wax bean, swamp cabbage, peanut, and abalone. An alpha,omega-dicarboxylic acid resulting from the formal oxidation of each of the terminal methyl groups of butane to the corresponding carboxy group. It is an intermediate metabolite in the citric acid cycle. COVID info from PDB, Protein Data Bank Corona-virus Coronavirus SARS-CoV-2 COVID-19 SARS-CoV COVID19 SARS2 SARS Acquisition and generation of the data is financially supported in part by CREST/JST. KEIO_ID S004 Succinic acid is a potent and orally active anxiolytic agent. Succinic acid is an intermediate product of the tricarboxylic acid cycle. Succinic acid can be used as a precursor of many industrially important chemicals in food, chemical and pharmaceutical industries[1][2]. Succinic acid is a potent and orally active anxiolytic agent. Succinic acid is an intermediate product of the tricarboxylic acid cycle. Succinic acid can be used as a precursor of many industrially important chemicals in food, chemical and pharmaceutical industries[1][2].

   

Oxoglutaric acid

2-oxopentanedioic acid

C5H6O5 (146.0215)


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

   

Aconitate [cis or trans]

(1Z)-prop-1-ene-1,2,3-tricarboxylic acid

C6H6O6 (174.0164)


cis-Aconitic acid is an intermediate in the tricarboxylic acid cycle produced by the dehydration of citric acid. The enzyme aconitase (aconitate hydratase; EC 4.2.1.3) catalyses the stereo-specific isomerization of citrate to isocitrate via cis-aconitate in the tricarboxylic acid cycle. Present in apple fruits, maple syrup and passion fruit juice cis-Aconitic acid, also known as (Z)-aconitic acid, plays several important biological roles: Intermediate in the Citric Acid Cycle: cis-Aconitic acid is an intermediate in the tricarboxylic acid (TCA) cycle, also known as the Krebs cycle or citric acid cycle. It is formed from citrate by the enzyme aconitase and is rapidly converted into isocitrate, another key intermediate in the cycle. The TCA cycle is central to cellular respiration, generating energy-rich molecules like NADH and FADH2. Regulation of Aconitase Activity: The conversion of citrate to cis-aconitate and then to isocitrate by aconitase is an important regulatory step in the TCA cycle. This conversion helps in maintaining the balance of the cycle and is influenced by factors like the energy status of the cell. Role in Cholesterol Synthesis: cis-Aconitic acid is also involved in the synthesis of cholesterol. It serves as a precursor for the synthesis of mevalonate, a key intermediate in the cholesterol biosynthesis pathway. Potential Involvement in Disease: Altered metabolism or accumulation of cis-aconitic acid has been associated with certain diseases, including neurodegenerative disorders and cancer. Its role in these conditions is an area of ongoing research. Plant Growth and Development: In plants, cis-aconitic acid has been found to play a role in growth and development, including seed germination and leaf senescence. In summary, cis-aconitic acid is a crucial intermediate in the TCA cycle, impacting energy production and various metabolic pathways in cells. Its role extends to cholesterol synthesis and potentially to various disease processes, highlighting its importance in cellular metabolism and physiology. cis-Aconitic acid. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=585-84-2 (retrieved 2024-07-01) (CAS RN: 585-84-2). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). (Z)-Aconitic acid (cis-Aconitic acid) is the cis-isomer of Aconitic acid. (Z)-Aconitic acid (cis-Aconitic acid) is an intermediate in the tricarboxylic acid cycle produced by the dehydration of citric acid. (Z)-Aconitic acid (cis-Aconitic acid) is the cis-isomer of Aconitic acid. (Z)-Aconitic acid (cis-Aconitic acid) is an intermediate in the tricarboxylic acid cycle produced by the dehydration of citric acid.

   

DL-Malic acid

2-Hydroxyethane-1,2-dicarboxylic acid

C4H6O5 (134.0215)


Malic acid (CAS: 6915-15-7) is a tart-tasting organic dicarboxylic acid that plays a role in many sour or tart foods. Apples contain malic acid, which contributes to the sourness of a green apple. Malic acid can make a wine taste tart, although the amount decreases with increasing fruit ripeness (Wikipedia). In its ionized form, malic acid is called malate. Malate is an intermediate of the TCA cycle along with fumarate. It can also be formed from pyruvate as one of the anaplerotic reactions. In humans, malic acid is both derived from food sources and synthesized in the body through the citric acid cycle or Krebs cycle which takes place in the mitochondria. Malates importance to the production of energy in the body during both aerobic and anaerobic conditions is well established. Under aerobic conditions, the oxidation of malate to oxaloacetate provides reducing equivalents to the mitochondria through the malate-aspartate redox shuttle. During anaerobic conditions, where a buildup of excess reducing equivalents inhibits glycolysis, malic acids simultaneous reduction to succinate and oxidation to oxaloacetate is capable of removing the accumulating reducing equivalents. This allows malic acid to reverse hypoxias inhibition of glycolysis and energy production. In studies on rats, it has been found that only tissue malate is depleted following exhaustive physical activity. Other key metabolites from the citric acid cycle needed for energy production were found to be unchanged. Because of this, a deficiency of malic acid has been hypothesized to be a major cause of physical exhaustion. Notably, the administration of malic acid to rats has been shown to elevate mitochondrial malate and increase mitochondrial respiration and energy production. Malic acid has been found to be a metabolite in Aspergillus (Hugo Vanden Bossche, D.W.R. Mackenzie and G. Cauwenbergh. Aspergillus and Aspergillosis, 1987). Acidulant, antioxidant, flavouring agent, flavour enhancer. Not for use in baby foods (GRAS) Malic acid. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=617-48-1 (retrieved 2024-07-01) (CAS RN: 6915-15-7). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). (S)-Malic acid ((S)-2-Hydroxysuccinic acid) is a dicarboxylic acid in naturally occurring form, contributes to the pleasantly sour taste of fruits and is used as a food additive. (S)-Malic acid ((S)-2-Hydroxysuccinic acid) is a dicarboxylic acid in naturally occurring form, contributes to the pleasantly sour taste of fruits and is used as a food additive. Malic acid (Hydroxybutanedioic acid) is a dicarboxylic acid that is naturally found in fruits such as apples and pears. It plays a role in many sour or tart foods. Malic acid (Hydroxybutanedioic acid) is a dicarboxylic acid that is naturally found in fruits such as apples and pears. It plays a role in many sour or tart foods.

   

Oxaloacetate

2-oxobutanedioic acid

C4H4O5 (132.0059)


Oxalacetic acid, also known as oxaloacetic acid, keto-oxaloacetate or 2-oxobutanedioate, belongs to the class of organic compounds known as short-chain keto acids and derivatives. These are keto acids with an alkyl chain the contains less than 6 carbon atoms. Oxalacetic acid is a metabolic intermediate in many processes that occur in animals and plants. It takes part in gluconeogenesis, the urea cycle, the glyoxylate cycle, amino acid synthesis, fatty acid synthesis and the citric acid cycle. Oxalacetic acid exists in all living species, ranging from bacteria to plants to humans. Within humans, oxalacetic acid participates in a number of enzymatic reactions. In particular, oxalacetic acid is an intermediate of the citric acid cycle, where it reacts with acetyl-CoA to form citrate, catalyzed by citrate synthase. It is also involved in gluconeogenesis and the urea cycle. In gluconeogenesis oxaloacetate is decarboxylated and phosphorylated by phosphoenolpyruvate carboxykinase and becomes 2-phosphoenolpyruvate using guanosine triphosphate (GTP) as phosphate source. In the urea cycle, malate is acted on by malate dehydrogenase to become oxaloacetate, producing a molecule of NADH. After that, oxaloacetate can be recycled to aspartate, as this recycling maintains the flow of nitrogen into the cell. In mice, injections of oxalacetic acid have been shown to promote brain mitochondrial biogenesis, activate the insulin signaling pathway, reduce neuroinflammation and activate hippocampal neurogenesis (PMID: 25027327). Oxalacetic acid has also been reported to reduce hyperglycemia in type II diabetes and to extend longevity in C. elegans (PMID: 25027327). Outside of the human body, oxalacetic acid has been detected, but not quantified in, several different foods, such as Persian limes, lemon balms, wild rice, canola, and peanuts. This could make oxalacetic acid a potential biomarker for the consumption of these foods. Oxalacetic acid, also known as ketosuccinic acid or oxaloacetate, belongs to short-chain keto acids and derivatives class of compounds. Those are keto acids with an alkyl chain the contains less than 6 carbon atoms. Thus, oxalacetic acid is considered to be a fatty acid lipid molecule. Oxalacetic acid is soluble (in water) and a moderately acidic compound (based on its pKa). Oxalacetic acid can be synthesized from succinic acid. Oxalacetic acid can also be synthesized into oxaloacetic acid 4-methyl ester. Oxalacetic acid can be found in a number of food items such as daikon radish, sacred lotus, cucurbita (gourd), and tarragon, which makes oxalacetic acid a potential biomarker for the consumption of these food products. Oxalacetic acid can be found primarily in cellular cytoplasm, cerebrospinal fluid (CSF), and urine, as well as in human liver tissue. Oxalacetic acid exists in all living species, ranging from bacteria to humans. In humans, oxalacetic acid is involved in several metabolic pathways, some of which include the oncogenic action of succinate, the oncogenic action of 2-hydroxyglutarate, glycogenosis, type IB, and the oncogenic action of fumarate. Oxalacetic acid is also involved in several metabolic disorders, some of which include the oncogenic action of l-2-hydroxyglutarate in hydroxygluaricaciduria, transfer of acetyl groups into mitochondria, argininemia, and 2-ketoglutarate dehydrogenase complex deficiency. Moreover, oxalacetic acid is found to be associated with anoxia. C274 - Antineoplastic Agent > C177430 - Agent Targeting Cancer Metabolism C26170 - Protective Agent > C1509 - Neuroprotective Agent Oxaloacetic acid (2-Oxosuccinic acid) is a metabolic intermediate involved in several ways, such as citric acid cycle, gluconeogenesis, the urea cycle, the glyoxylate cycle, amino acid synthesis, and fatty acid synthesis[1][2]. Oxaloacetic acid. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=328-42-7 (retrieved 2024-10-17) (CAS RN: 328-42-7). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0).

   

Isocitric acid

3-carboxy-2,3-dideoxy-1-hydroxypropan-1,2,3-tricarboxylic acid

C6H8O7 (192.027)


Isocitric acid, also known as isocitrate belongs to the class of organic compounds known as tricarboxylic acids and derivatives. These are carboxylic acids containing exactly three carboxyl groups. Isocitric acid is a TCA (tricarboxylic acid) cycle intermediate. It is a structural isomer of citric acid and is formed from citrate with the help of the enzyme aconitase. More specifically, Isocitric acid is synthesized from citric acid via the intermediate cis-aconitic acid by the enzyme aconitase (aconitate hydratase). Isocitrate is acted upon by isocitrate dehydrogenase (IDH) to form alpha-ketoglutarate. This is a two-step process, which involves oxidation of isocitrate to oxalosuccinate (a ketone), followed by the decarboxylation of the carboxyl group beta to the ketone, forming alpha-ketoglutarate. In humans, IDH exists in three isoforms: IDH3 catalyzes the third step of the citric acid cycle while converting NAD+ to NADH in the mitochondria. The isoforms IDH1 and IDH2 catalyze the same reaction outside the context of the citric acid cycle and use NADP+ as a cofactor instead of NAD+. They localize to the cytosol as well as the mitochondrion and peroxisome. Isocitric acid exists in all living species, ranging from bacteria to plants to humans. Isocitric acid is a minor organic acid found in most fruit juices, especially in blackberries, youngberries, and boyberries, and in vegetables, especially in carrots. The determination of D-isocitric acid has become of importance in the analysis of fruit juices for the detection of illegal additives (adulteration). Since the quantities of citric and isocitric acids are correlated in fruit juices, a high ratio of citric to isocitric acid can indicate the addition of citric acid as an alduterant. In authentic orange juice, for example, the ratio of citric acid to D-isocitric acid is usually less than 130. Isocitric acid is mostly used in the food industry (food additive) as a food acidulant. The citrate oxidation to isocitrate is catalyzed by the enzyme aconitase. Human prostatic secretion is remarkably rich in citric acid and low aconitase activity will therefore play a significant role in enabling accumulation of high citrate levels (PubMed ID 8115279) [HMDB]. Isocitric acid is found in many foods, some of which are wild carrot, redcurrant, carrot, and soursop. [Spectral] Isocitrate (exact mass = 192.027) and CDP (exact mass = 403.01818) 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. Isocitric acid. CAS Common Chemistry. CAS, a division of the American Chemical Society, n.d. https://commonchemistry.cas.org/detail?cas_rn=320-77-4 (retrieved 2024-07-01) (CAS RN: 320-77-4). Licensed under the Attribution-Noncommercial 4.0 International License (CC BY-NC 4.0). Isocitric acid is an endogenous metabolite present in Saliva and Cellular_Cytoplasm that can be used for the research of Alzheimer's Disease, Lewy Body Dementia and Anoxia[1][2][3]. Isocitric acid is an endogenous metabolite present in Saliva and Cellular_Cytoplasm that can be used for the research of Alzheimer's Disease, Lewy Body Dementia and Anoxia[1][2][3].

   

Succinyl-CoA

4-[(2-{3-[(2R)-3-[({[({[(2R,3S,4R,5R)-5-(6-amino-9H-purin-9-yl)-4-hydroxy-3-(phosphonooxy)oxolan-2-yl]methoxy}(hydroxy)phosphoryl)oxy](hydroxy)phosphoryl}oxy)methyl]-2-hydroxy-3-methylbutanamido]propanamido}ethyl)sulfanyl]-4-oxobutanoic acid

C25H40N7O19P3S (867.1312)


Succinyl-CoA is an important intermediate in the citric acid cycle, where it is synthesized from α-Ketoglutarate by α-ketoglutarate dehydrogenase (EC 1.2.4.2) through decarboxylation, and is converted into succinate through the hydrolytic release of coenzyme A by succinyl-CoA synthetase (EC 6.2.1.5). Succinyl-CoA may be an end product of peroxisomal beta-oxidation of dicarboxylic fatty acids; the identification of an apparently specific succinyl-CoA thioesterase (ACOT4, EC 3.1.2.3, hydrolyzes succinyl-CoA) in peroxisomes strongly suggests that succinyl-CoA is formed in peroxisomes. Acyl-CoA thioesterases (ACOTs) are a family of enzymes that catalyze the hydrolysis of the CoA esters of various lipids to the free acids and coenzyme A, thereby regulating levels of these compounds. (PMID: 16141203) [HMDB]. Succinyl-CoA is found in many foods, some of which are fruits, sea-buckthornberry, pomegranate, and sweet orange. Succinyl-CoA is an important intermediate in the citric acid cycle, where it is synthesized from α-Ketoglutarate by α-ketoglutarate dehydrogenase (EC 1.2.4.2) through decarboxylation, and is converted into succinate through the hydrolytic release of coenzyme A by succinyl-CoA synthetase (EC 6.2.1.5). Succinyl-CoA may be an end product of peroxisomal beta-oxidation of dicarboxylic fatty acids; the identification of an apparently specific succinyl-CoA thioesterase (ACOT4, EC 3.1.2.3, hydrolyzes succinyl-CoA) in peroxisomes strongly suggests that succinyl-CoA is formed in peroxisomes. Acyl-CoA thioesterases (ACOTs) are a family of enzymes that catalyze the hydrolysis of the CoA esters of various lipids to the free acids and coenzyme A, thereby regulating levels of these compounds. (PMID: 16141203).