Question

Question: Why does it make metabolic sense for the cell to regulate the activity of acetyl-CoA carboxylase?

Short answer

The regulation of acetyl-CoA carboxylase activity makes metabolic sense because it catalyzes malonyl-CoA production, which is a rate-limiting step of fatty acid synthesis.

Step-by-step solution

Acetyl-CoA carboxylase

The enzyme that is involved in the production of malonyl CoA from acetyl-CoA is known as acetyl-CoA carboxylase. In the first step, the enzyme activates the${\mathrm{CO}}_2$, and in the second step, the enzyme carboxylates the acetyl-CoA.

Regulation of acetyl-CoA carboxylase

The regulation of the activity of acetyl-CoA carboxylase occurs by both allosteric and hormonal molecules in mammals. The regulation of this enzyme makes metabolic sensebecause it catalyzes the rate-limiting step in the fatty acid biosynthesis. Malonyl-CoA is required during synthesis for the transfer of malonyl to the acyl carrier protein (ACP). Therefore, the decrease in malonyl-CoA production will decrease fatty acid synthesis.