Description
Acetyl-coenzyme A (acetyl-
CoA), the thioester of CoA and acetic acid, is a pivotal molecule in biological systems. Foremost, it serves as a source of carbon for the Krebs cycle, for the synthesis of fatty acids, and for isoprenoid-
based protein modifications. Acetyl-
CoA also serves as an intermediate in oxidation of fatty acids and amino acids and is formed by the oxidative decarboxylation of pyruvate in mitochondria. It is an essential cofactor or substrate for acetyltransferases and acyltransferases, as in the post-
translational modification of proteins and in the synthesis of the neurotransmitter acetylcholine.
Uses
Acetyl-Coenzyme A is used to assay CAT enzyme activity in cell extracts using radioisotopes. CAT enzyme activity in cell extracts catalyzes the transfer of acetyl groups from acetylcoenzyme A to chloramphenicol. A number of assays have been developed to measure CAT activity in cell extracts. Acetyl-Coenzyme A has also been used to determine citrate synthase activity.
General Description
Acetyl-Coenzyme A, trilithium salt
Biochem/physiol Actions
Acetyl-Coenzyme A (Ac-CoA) is the end product of glycolysis and takes part in the Ac-CoA pathway, which is a metabolic pathway for carbon compounds. Ac-CoA is important in cholesterol synthesis. It also takes part in fatty acid biosynthesis and catabolism of polyamines like spermine and spermidine. A low level of Ac-CoA leads to a loss in glial cell and neuronal function. Ketone bodies and triglycerides give rise to Ac-CoA on hydrolysis and this indirectly leads to increased histone acetylation.
Metabolism
Acetyl coenzyme A, the precursor of the acetate-malonare pathway, is a metabolite of extreme importance in both primary and secondary metabolism. In every living organism, there exists a metabolie pool of acetyl CoA which is continually replenished and depleted. Glycolysis and the catabolism of fatty acids and amino acids produce acetyl CoA, while this compound is the precursor of a host of primary and secondary metabolites, including fatty acids, terpenoids, steroids, polyketides, aromatic compounds and acetyl esters and amides. The conversion of acetyl CoA to citrate and other tricarboxylic acids leads to the formation of the amino acids and their products, such as the nucleic acids and alkaloids.
Acetyl CoA is also central to the catabolism of glucose and the fatty acids, which, through the tricarboxylic acid cycle, are the main reaction sequences producing the energy necessary for metabolie processes.
In plants, an enzyme, acetyl CoA synthetase, catalyses the formation of the thiol ester from acetate.
