Fluoroacetate poisoning causes TCA cycle arrest. The toxic mechanism involves conversion of fluocoacetate to fluorocitrate, which specifically inhibits which enzyme?

• A Citrate synthase
• B Isocitrate dehydrogenase
• C Alpha-ketoglutarate dehydrogenase
• D Aconitase ✓

Explanation

Fluoroacetate is converted to fluoroacetyl-CoA, which enters the TCA cycle and is condensed with oxaloacetate to form fluorocitrate by citrate synthase. Fluorocitrate tightly binds and inhibits aconitase, blocking the conversion of citrate to isocitrate. This classic poisoning mechanism causes citrate accumulation. Distractor A is wrong because citrate synthase actually acts on fluoroacetate, not the target of toxicity.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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