Question

Which one of the following is a coenzyme?

• A. Nicotinamide
• B. Riboflavin
• C. Pantothenic acid
• D. All of the above

Answer 1

Answer: (D)

All of the above

Coenzymes are the non-protein part of an enzyme. These are organic molecules that bind with the protein molecule to form the active enzyme. Nicotinamide, riboflavin and pantothenic acid are coenzymes that attach with the apoenzyme and accelerate the reaction.

Nicotinamide gets incorporated in NAD${}^{+}$ acts as an electron acceptor in metabolic reaction. It acts as a coenzyme for a biological reaction like glycolysis. During glycolysis, it accepts the electron and hydrogen, changes to NADH and generates ATP.

Riboflavin is a water-soluble vitamin B${}_2$. It is an integral component of coenzyme flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN).

Pantothenic acid is a water-soluble vitamin B${}_5$. It is required by the enzyme pyruvate dehydrogenase to synthesize coenzyme-A (CoA) which is a primary substrate for the Krebs cycle. Pantothenic acid is a precursor for the synthesis of coenzyme A (CoA, CoASH) and forms part of the “swinging sulfhydryl arm” of the fatty acid synthase complex.

So, the correct answer is option D.