betaketoasilCoA

Beta-ketoacyl-CoA, also called 3-oxoacyl-CoA, is a thioester formed when Coenzyme A is bound to a beta-ketoacyl moiety. It is an intermediate in fatty acid beta-oxidation in both mitochondria and peroxisomes, and it can also appear in some anabolic pathways.

In the beta-oxidation sequence, acyl-CoA dehydrogenase introduces a double bond to form trans-Δ2-enoyl-CoA, which is hydrated by enoyl-CoA hydratase to 3-hydroxyacyl-CoA. The enzyme beta-hydroxyacyl-CoA dehydrogenase then oxidizes this intermediate to beta-ketoacyl-CoA. Beta-ketoacyl-CoA thiolase (also called thiolase) cleaves beta-ketoacyl-CoA with CoA-SH to yield acetyl-CoA and a shortened acyl-CoA two carbons shorter, allowing the cycle to continue.

Chemically, beta-ketoacyl-CoA has the general structure R-CO-CH2-CO-S-CoA, where R represents the remainder of the fatty acyl chain. The term encompasses various chain lengths and substitutions encountered during metabolism.

Beta-ketoacyl-CoA is a transient intermediate that channels carbon into energy production, as acetyl-CoA enters the tricarboxylic acid cycle. In cells, beta-oxidation occurs primarily in mitochondria, with peroxisomes handling very long-chain substrates. Defects in beta-oxidation enzymes can disrupt energy metabolism and are associated with metabolic disorders.