Question

9. a. Describe the various ways that Acetyl-CoA Carboxylase, the first committed step of fatty acid biosynthesis, is regulated.

b. Predict whether this enzyme is likely to be active in the fed state or the fasted state, and provide a rationale for how this activation occurs given your answer to part a.

Answer 1

Acetyl CoA Carboxylase can be regulated in the following ways:

1. Hormones and environmental stress in the cells : Certain hormones like insulin increses the activity of the enzyme whereas stress decreases the activity.
2. Phosphorylation and dephosphorylation:Acetyl CoA carboxylase has 2 subunits Alpha and beta.Phosphorylation of the alpha subunit inactivates the enzyme and dephosphorylation activates it.
3. Substrate supply and allosteric ligand also regulate the activity.

The enzyme is active in the fed state as more glucose results in increase in glycolysis and more production of acetyl CoA which is the substrate for the enzyme.