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| Names | |
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| Preferred IUPAC name O1-{(3R)-4-[(3-{[2-(Acetylsulfanyl)ethyl]amino}-3-oxopropyl)amino]-3-hydroxy-2,2-dimethyl-4-oxobutyl}O3-{[(2R,3S,4R,5R)-5-(6-amino-9H-purin-9-yl)-4-hydroxy-3-(phosphonooxy)oxolan-2-yl]methyl} dihydrogen diphosphate | |
| Identifiers | |
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3D model (JSmol) | |
| ChEBI | |
| ChemSpider |
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| ECHA InfoCard | 100.000.719 |
| KEGG |
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| MeSH | Acetyl+Coenzyme+A |
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| Properties | |
| C23H38N7O17P3S | |
| Molar mass | 809.57 g·mol−1 |
| UV-vis (λmax) | 260 nm; 232 nm[1] |
| Absorbance | ε260 = 16.4 mM−1 cm−1 (adenosine)[1] ε232 = 8.7 mM−1 cm−1 (thioester)[1] Δε232 on thioester hydrolysis = −4.5 mM−1 cm−1[1] |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Acetyl-CoA (acetyl coenzyme A) is a molecule that participates in manybiochemical reactions in protein, carbohydrate and lipidmetabolism.[2] Its main function is to deliver theacetyl group to thecitric acid cycle (Krebs cycle) to beoxidized for energy production.
Coenzyme A (CoASH or CoA) consists of aβ-mercaptoethylamine group linked topantothenic acid (vitamin B5) through anamide linkage[3] and 3'-phosphorylated ADP. The acetyl group (indicated in blue in the structural diagram on the right) of acetyl-CoA is linked to thesulfhydryl substituent of the β-mercaptoethylamine group. Thisthioester linkage is a "high energy" bond, which is particularly reactive.Hydrolysis of the thioester bond isexergonic (−31.5 kJ/mol).
CoA is acetylated to acetyl-CoA by the breakdown ofcarbohydrates throughglycolysis and by the breakdown offatty acids throughβ-oxidation. Acetyl-CoA then enters the citric acid cycle, where the acetyl group is oxidized to carbon dioxide and water, and the energy released is captured in the form of 11ATP and oneGTP per acetyl group.
Konrad Bloch andFeodor Lynen were awarded the 1964Nobel Prize in Physiology or Medicine for their discoveries linking acetyl-CoA and fatty acid metabolism.Fritz Lipmann won the Nobel Prize in 1953 for his discovery of the cofactorcoenzyme A.[4]
Acetyl-CoA is ametabolic intermediate that is involved in many metabolic pathways in an organism. It is produced during the breakdown ofglucose,fatty acids, andamino acids, and is used in the synthesis of many otherbiomolecules, includingcholesterol,fatty acids, andketone bodies. Acetyl-CoA is also a key molecule in thecitric acid cycle, which is a series of chemical reactions that occur in themitochondria of cells and is responsible for generating energy in the form ofATP.[5][6]
In addition, acetyl-CoA is a precursor for the biosynthesis of various acetyl-chemicals, acting as an intermediate to transfer an acetyl group during the biosynthesis of those acetyl-chemicals. Acetyl-CoA is also involved in the regulation of various cellular mechanisms by providing acetyl groups to target amino acid residues for post-translationalacetylation reactions of proteins.
The acetylation of CoA is determined by the carbon sources.[7][8]
At highglucose levels,glycolysis takes place rapidly, thus increasing the amount ofcitrate produced from thecitric acid cycle. This citrate is then exported to otherorganelles outside the mitochondria to be broken into acetyl-CoA andoxaloacetate by theenzymeATP citrate lyase (ACL). This principal reaction is coupled with thehydrolysis of ATP.[9][10]
At low glucose levels CoA is acetylated usingacetate byacetyl-CoA synthetase (ACS), also coupled withATP hydrolysis.[11]Ethanol also serves as a carbon source for acetylation of CoA utilizing the enzymealcohol dehydrogenase.[12] Degradation of branched-chainketogenicamino acids such asvaline,leucine, andisoleucine occurs. These amino acids are converted to α-ketoacids bytransamination and eventually toisovaleryl-CoA through oxidative decarboxylation by an α-ketoacid dehydrogenase complex. Isovaleryl-CoA undergoesdehydrogenation,carboxylation and hydration to form another CoA-derivative intermediate before it is cleaved into acetyl-CoA andacetoacetate.[13][page needed]
At high glucose levels, acetyl-CoA is produced throughglycolysis.[14]Pyruvate undergoes oxidative decarboxylation in which it loses itscarboxyl group (ascarbon dioxide) to form acetyl-CoA, giving off 33.5 kJ/mol of energy. The oxidative conversion of pyruvate into acetyl-CoA is referred to as thepyruvate dehydrogenase reaction. It is catalyzed by thepyruvate dehydrogenase complex. Other conversions between pyruvate and acetyl-CoA are possible. For example,pyruvate formate lyasedisproportionates pyruvate into acetyl-CoA andformic acid.
At low glucose levels, the production of acetyl-CoA is linked toβ-oxidation offatty acids. Fatty acids are first converted to acyl-CoA. Acyl-CoA is then degraded in a four-step cycle ofoxidation,hydration,oxidation andthiolysis catalyzed by four respective enzymes, namelyacyl-CoA dehydrogenase,enoyl-CoA hydratase,3-hydroxyacyl-CoA dehydrogenase, andthiolase. The cycle produces a new fatty acid chain with two fewer carbons and acetyl-CoA as a byproduct.[15]
| Click on genes, proteins and metabolites below to visitGene Wiki pages and related Wikipedia articles. The pathway can be downloaded and edited atWikiPathways. |
[[File:  [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] [[]] TCACycle_WP78edit |
this process is outlined graphically in page 73
{{cite journal}}: CS1 maint: DOI inactive as of December 2024 (link)
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