Pantothenic acid (vitamin B5) is a component of coenzyme A. During World War II, prisoners of war in Southeast Asia developed a syndrome of painful burning feet. Pantothenic acid deficiency is rare but can occur in severe malnutrition. Which enzymatic step directly depends on coenzyme A derived from pantothenic acid?

• A Conversion of pyruvate to acetyl-CoA by pyruvate dehydrogenase
• B Transfer of acyl groups into mitochondria via the carnitine shuttle ✓
• C Carboxylation of pyruvate to oxaloacetate by pyruvate carboxylase
• D Oxidation of succinate to fumarate in the TCA cycle

Explanation

Coenzyme A (derived from pantothenic acid) is essential for the carnitine shuttle. Carnitine palmitoyltransferase I transfers the acyl group from CoA to carnitine, enabling long-chain fatty acid entry into mitochondria for beta-oxidation. Pantothenic acid deficiency impairs this, causing the burning feet syndrome due to defective energy metabolism in nerves. Option A uses TPP, not CoA, as the direct cofactor, though CoA accepts the product.

Reference: Lehninger Principles of Biochemistry, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.