In metabolic processes, what molecule is produced as a byproduct during the reaction of acetyl-CoA with CO2 catalyzed by ACC2?

• A. Malonyl-CoA
• B. Glucose
• C. Fatty acyl-CoA
• D. Acetate

Answer: (A)

In the reaction catalyzed by Acetyl-CoA Carboxylase 2 (ACC2), acetyl-CoA reacts with carbon dioxide (CO2) to produce malonyl-CoA. This process is an essential step in the biosynthesis of fatty acids.

During this reaction, an acetyl group from acetyl-CoA is carboxylated, meaning that a CO2 molecule is added to it, converting it into malonyl-CoA, which contains a three-carbon unit. This three-carbon compound (malonyl-CoA) acts as a building block during fatty acid synthesis, where it undergoes further reactions to extend the carbon chain.

Malonyl-CoA not only provides building blocks for fatty acid synthase but also plays a regulatory role, as it inhibits the transport of fatty acids into the mitochondria, thereby influencing energy metabolism and fat storage. This reaction represents a key regulatory step in the overall metabolic pathway of lipogenesis.

In contrast to this process and the role of ACC2, the other listed options—glucose, fatty acyl-CoA, and acetate—do not directly result from the reaction involving acetyl-CoA and CO2 catalyzed by ACC2. Glucose is a