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Coenzyme A (CoA, SHCoA, CoASH) is a coenzyme, notable for its role in the synthesis and oxidation of fatty acids, and the oxidation of pyruvate in the citric acid cycle.All genomes sequenced to date encode enzymes that use coenzyme A as a substrate, and around 4% of cellular enzymes use it (or a thioester) as a substrate.
Coenzyme A (CoASH or CoA) consists of a β-mercaptoethylamine group linked to pantothenic acid (vitamin B5) through an amide 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 the sulfhydryl substituent of the β-mercaptoethylamine group.
The following other wikis use this file: Usage on ar.wikipedia.org مرافق الإنزيم-أ; Usage on bs.wikipedia.org Koenzim A; Usage on cs.wikipedia.org
Coenzyme A transferases (CoA-transferases) are transferase enzymes that catalyze the transfer of a coenzyme A group from an acyl-CoA donor to a carboxylic acid acceptor. [ 1 ] [ 2 ] Among other roles, they are responsible for transfer of CoA groups during fermentation and metabolism of ketone bodies .
General chemical structure of an acyl-CoA, where R is a carboxylic acid side chain. Acyl-CoA is a group of CoA-based coenzymes that metabolize carboxylic acids. Fatty acyl-CoA's are susceptible to beta oxidation, forming, ultimately, acetyl-CoA.
Energy-generating ions and molecules, such as amino acids and carbohydrates, enter the Krebs cycle as acetyl coenzyme A and oxidize in the cycle. [5] The pyruvate dehydrogenase complex (PDC) catalyzes the decarboxylation of pyruvate, resulting in the synthesis of acetyl-CoA, CO 2 , and NADH .
The two molecules joined that make up acetyl-CoA are acetate and coenzyme A (CoA). The complete reaction with all the substrates and products included is: ATP + Acetate + CoA → AMP + Pyrophosphate + Acetyl-CoA [1] Once acetyl-CoA is formed it can be used in the TCA cycle in aerobic respiration to produce energy and electron carriers.
coenzyme-A comes in and undergoes hydrogen-atom transfer with the Cys419 radical to generate a coenzyme-A radical. The coenzyme-A radical then picks up the acetyl group from Cys418 to generate acetyl-CoA, leaving behind a Cys418 radical. Pyruvate formate lyase can then undergo radical transfer to put the radical back onto Gly734.