Which enzyme acts as the rate-limiting step in the synthesis of fatty acids?

Explanation

The key regulatory enzyme controlling fatty acid synthesis is acetyl-CoA carboxylase, which catalyzes the carboxylation of acetyl-CoA to malonyl-CoA, marking the rate-limiting step. Other enzymes like acetoacetate synthetase and acyl transferase participate in different metabolic pathways, while biotin serves as a cofactor but is not the limiting enzyme.