Trivalent arsenicals such as arsenite poison cells by binding tightly to a specific functional group of two mitochondrial multienzyme complexes. Which moiety does arsenite target?

• A The biotin prosthetic group
• B The thiamine pyrophosphate cofactor
• C The FAD cofactor
• D The sulfhydryl groups of lipoamide ✓

Explanation

Arsenite forms stable bonds with vicinal sulfhydryl groups of the reduced lipoamide arm shared by the pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase complexes. Blocking the swinging lipoyl group halts transfer of the acyl group to CoA, so both complexes fail. Biotin belongs to carboxylases, TPP is not the arsenite target, and FAD is not attacked by trivalent arsenic.

Reference: Lippincott Illustrated Reviews: Biochemistry, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.