What is the function of B-ketoacyl-ACP synthase (KS) in biosynthesis of fatty acids? What is the...

What is the function of B-ketoacyl-ACP synthase (KS) in biosynthesis of fatty acids? What is the mechanism?

Expert Solution

Beta-ketoacyl-ACP synthase is an enzyme which is involved in the synthesis of fatty acid. It uses malonyl-CoA as a carbon source to elongate the ACP-bound acyl species, which results in the formation of ACP-bound β-ketoacyl species such as the acetoacetyl-ACP

Mechanism : The Cys171 of active site attacks the acetyl ACP's carbonyl, and then stabilizes the intermediate with other residues in the active site. ACP is then eliminated, and it deprotonates His311 in this process. A thioester is then regenerated with cysteine in the active site. Decarboxylation of a malonyl CoA which is also in the active site initially creates an enolate, which is then stabilized by His311 and His345. The enolate tautomerizes to a carbanion which attacks the thioester of the acetyl-enzyme complex.

Another proposed mechanism is the creation of a tetrahedral transition state. The driving force of reaction comes from decarboxylation of malonyl ACP.

gladiator answered 3 months ago

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