Higher organisms have eenzymes of fatty acids that are present in a fatty acid synthase which is a single polypeptide chain. The fatty acid synthase is composed of acetyl CoA, malonyl CaA, and NADPH. The enzyme catalyzes the synthesis of long-chain fatty acids. In bacteria, the fatty acid synthase dossociates into individual enzymes when cells degrade.
The formation of acetyl ACP and malonyl ACP take part in the elongation of fatty acids through two enzymes, acetyl transacylase and malonyl transacylase. Acetyl transacylase tranfers acyl group, and malonyl transacylase is highly specific. The two ACP molecules react to form acetoacetyl ACP.