Zinc is a cofactor for multiple metalloenzymes. Which enzyme's activity is classically used as a FUNCTIONAL biomarker of zinc status in clinical biochemistry?
- A Glutathione peroxidase (reflects selenium status)
- B Alkaline phosphatase (zinc-dependent enzyme that decreases with zinc deficiency) ✓
- C Xanthine oxidase (reflects molybdenum status)
- D Ceruloplasmin (reflects copper status)
Correct answer: B. Alkaline phosphatase (zinc-dependent enzyme that decreases with zinc deficiency)
Explanation
Alkaline phosphatase is a zinc metalloenzyme that requires zinc at its active site for catalysis. Serum alkaline phosphatase activity falls in zinc deficiency and rises with zinc repletion — making it a useful functional biomarker, although not perfectly specific. Serum zinc itself is unreliable due to redistribution during acute-phase response. Other zinc-dependent enzymes include carbonic anhydrase, carboxypeptidase, and alcohol dehydrogenase. Glutathione peroxidase is a selenium biomarker; ceruloplasmin is a copper biomarker.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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