Question

Pyruvate is converted to acetyl CoA by a unique enzyme known as

A) pyruvate decarboxylase.
B) pyruvate dehydrogenase complex.
C) transitionase system.
D) multiplex enzyme system.
E) pyruvate CoA transferase.

Answer 1

The enzyme that catalyzes the conversion of pyruvate to acetyl CoA is the pyruvate dehydrogenase complex, which involves decarboxylation, oxidation, and the transfer of the acetyl group to CoA. Option B) pyruvate dehydrogenase complex is the correct answer.

Step-by-step explanation:

Pyruvate is an important molecule that acts as a link between glycolysis and the Krebs cycle in cellular respiration. Upon entering the mitochondrial matrix, pyruvate undergoes a critical transformation catalyzed by a set of enzymes known collectively as the pyruvate dehydrogenase complex.

This complex performs several actions:

• Pyruvate dehydrogenase removes a carboxyl group from pyruvate, producing carbon dioxide.
• Dihydrolipoyl transacetylase oxidizes a hydroxyethyl group to form an acetyl group, which is important as it produces NADH, a carrier of electrons that can be used later in the electron transport chain to produce ATP.
• Then, an enzyme-bound acetyl group is transferred to Coenzyme A (CoA), resulting in the formation of acetyl-CoA, the molecule that enters the Krebs cycle.

The correct option for the enzyme that converts pyruvate to acetyl CoA is B) pyruvate dehydrogenase complex.