Question

Which of the following coenzymes participate in the reactions of the pyruvate dehydrogenase complex?

(A) thiamine pyrophosphate (TPP)
(B) lipoic acid (lipoamide)
(C) Flavin adenine dinucleotide (FAD)
(D) Nicotinamide adenine dinucleotide (NAD+)
(E) Coenzyme A (CoA)

Answer 1

The correct answer will be option- E.

Step-by-step explanation:

The pyruvate dehydrogenase is a multi-enzyme complex which catalyzes the irreversible reaction that is the decarboxylation of pyruvate to acetyl-CoA and formation of NADH, and CO₂. The complex is used for the entry of the pyruvate into the TCA cycle.

The enzyme complex is made up of two regulatory enzymes, three catalytic enzymes and a binding protein. The three enzymes are :

1. Pyruvate dehydrogenase (E1): uses thiamine pyrophosphate (TPP) as its prosthetic group.

2. Dihydrolipoyl transacetylase (E2): uses coenzyme A and lipoamide as its prosthetic groups.

3. Dihydrolipoyl dehydrogenase (E3): uses nicotinamide adenine dinucleotide (NAD+) and flavin adenine dinucleotide (FAD) as its cofactors.

Since E2 uses coenzyme A as its co-factors therefore the correct answer will be option E.