Question

Before the start of fatty acid elongation reactions, a malonyl-CoA is added on to the__________( name the protein/enzyme ) and an acetyl-CoA is added on to the __________( name the protein/enzyme)

Answer 1

In the initiation phase of fatty acid synthesis, malonyl-CoA and acetyl-CoA are attached to specific enzymes; malonyl-CoA attaches to ACP, and acetyl-CoA attaches to 3-ketoacyl-ACP synthase, beginning the process of chain elongation.

Step-by-step explanation:

Before the start of fatty acid elongation reactions, a malonyl-CoA is added on to the acyl carrier protein (ACP), and an acetyl-CoA is added on to the 3-ketoacyl-ACP synthase enzyme that contains a specific cysteine residue with an active -SH group. During fatty acid synthesis, acetyl-CoA is transferred to the -SH group of cysteine, while malonyl-CoA is transferred to the -SH group of ACP. The products of these transfers are acetyl-S-Cys and malonyl-S-ACP, respectively. The reaction proceeds with the help of 3-ketoacyl synthase, which catalyzes the condensation between acetyl-S-Cys and malonyl-S-ACP, forming acetoacetic-S-ACP, thus extending the fatty acid chain.