KetoacylCoAThiolase

KetoacylCoA thiolase, also known as acetyl-CoA acetyltransferase or simply thiolase, is an enzyme that plays a crucial role in the metabolism of fatty acids and ketone bodies. Specifically, it catalyzes the final step in the beta-oxidation of fatty acids, the cleavage of beta-ketoacyl-CoA into acetyl-CoA and a shorter acyl-CoA molecule. This reaction is reversible and also functions in the synthesis of ketone bodies from acetyl-CoA in the liver.

In the context of fatty acid breakdown, thiolase facilitates the release of acetyl-CoA, a key intermediate that can then enter the citric acid cycle for energy production or be used for other metabolic pathways. In ketogenesis, the enzyme reverses its action, condensing two molecules of acetyl-CoA to form acetoacetyl-CoA, the precursor to ketone bodies like acetoacetate and beta-hydroxybutyrate. These ketone bodies serve as an alternative fuel source for tissues such as the brain when glucose is scarce.

Genetic defects in ketoacylCoA thiolase can lead to metabolic disorders, including certain types of ketolytic disorders. The enzyme is found in various organisms, reflecting its fundamental importance in cellular energy metabolism across different life forms. Its activity is regulated by the availability of substrates and the energy status of the cell.