Final answer:
The enzyme that regulates the first step in the fatty acid synthesis pathway and acts as an allosteric enzyme is acetyl-CoA carboxylase (ACC).
Step-by-step explanation:
The first step in the pathway for fatty acid synthesis is catalyzed by the allosteric enzyme acetyl-CoA carboxylase (ACC). This enzyme is a principal regulator of the fatty acid synthesis pathway.
ACC catalyzes the formation of malonyl-CoA from acetyl-CoA and bicarbonate, which is the committed step in fatty acid synthesis. The regulation of acetyl-CoA carboxylase involves both allosteric control and covalent modification. Allosteric activation occurs in the presence of citrate, while allosteric inhibition is due to palmitoyl-CoA.
Moreover, the enzyme's activity is also controlled through phosphorylation by AMP Kinase and Protein Kinase A, and dephosphorylation encouraged by insulin-activated phosphatases, which promotes the assembly of the enzyme into a functional polymer.
The first step in the pathway for fatty acid synthesis is catalyzed by the enzyme acetyl-CoA carboxylase (ACC), which is an allosteric enzyme and the principal regulator of the pathway. ACC is responsible for converting acetyl-CoA to malonyl-CoA, a crucial step in fatty acid synthesis.