Acyl Carrier Protein

• Published in: The Journal of biological chemistry 1972-05, Vol.247 (10), p.3190-3198
• Main Authors: Alberts, Alfred W., Bell, Robert M., Vagelos, P. Roy
• Format: Article
• Language: English
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(19)45231-9

β-Ketoacyl-acyl carrier protein (ACP) synthetase catalyzes the chain elongation step of fatty acid biosynthesis, the condensation of fatty acyl-ACP with malonyl-ACP yielding β-ketoacyl-ACP, CO 2 , and ACP. This enzyme catalyzes two additional reactions, fatty acyl-CoA-ACP transacylation and the decarboxylation of malonyl-ACP to form acetyl-ACP and CO 2 . Both the β-ketoacyl-ACP synthetase and the fatty acyl-CoA-ACP transacylase reactions are inhibited by low levels of iodoacetamide, and this inhibition can be prevented by a prior incubation of the enzyme with fatty acyl-CoA compounds that are substrates in the transacylase reaction. These inhibition experiments suggest that the fatty acyl-ACP and fatty acyl-CoA may have a common site on the enzyme. The malonyl-ACP decarboxylase reaction is only partially inhibited by iodoacetamide. The findings presented help to explain the fatty acyl-CoA-dependent malonyl-CoA- 14 CO 2 exchange reaction catalyzed by β-ketoacyl-ACP synthetase.