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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.
Structural diagram of acetyl-CoA: The portion in blue, on the left, is the acetyl group; the portion in black is coenzyme A. The citric acid cycle is a metabolic pathway that connects carbohydrate, fat, and protein metabolism.
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 .
A 2016 study of the genomes of a set of bacteria and archaea suggested that the last universal common ancestor (LUCA) of all cells was using an ancient Wood–Ljungdahl pathway in a hydrothermal setting, [10] but more recent work challenges this conclusion as they argued that the previous study had "undersampled protein families, resulting in incomplete phylogenetic trees which do not reflect ...
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.
Coenzyme A is recycled at this step. When the body has no free carbohydrates available, fat must be broken down into acetyl-CoA in order to get energy. Under these conditions, acetyl-CoA cannot be metabolized through the citric acid cycle because the citric acid cycle intermediates (mainly oxaloacetate ) have been depleted to feed the ...
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.