Zinc is an essential cofactor for carbonic anhydrase. In severe zinc deficiency (as in acrodermatitis enteropathica), reduced zinc-dependent enzyme activity would impair which physiological process?

• A Fatty acid synthesis via reduced FAS complex activity
• B Carbon dioxide transport, acid-base regulation, and gastric acid production ✓
• C DNA polymerase activity and purine synthesis
• D Hemoglobin synthesis via reduced ALA dehydratase activity

Explanation

Carbonic anhydrase (CA) is a zinc metalloenzyme that catalyzes CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3−. It is critical for: CO2 transport from tissues to lungs (in RBCs), renal tubular acid secretion (distal nephron), gastric parietal cell H+ secretion (via CA II), and pancreatic HCO3− secretion. Zinc deficiency in acrodermatitis enteropathica (SLC39A4 mutation) additionally impairs multiple zinc-finger transcription factors, matrix metalloproteinases, alcohol dehydrogenase, and taste sensation. ALA dehydratase is zinc-dependent and involved in heme synthesis (option D has some basis) but its impairment is less clinically prominent than CO2/acid-base physiology.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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