Ceruloplasmin contributes to antioxidant defence by virtue of which enzymatic activity?
- A It oxidises Fe2+ to Fe3+, limiting hydroxyl radical formation ✓
- B It reduces Cu2+ to Cu+, preventing lipid peroxidation
- C It decomposes hydrogen peroxide to water and oxygen
- D It scavenges superoxide anion directly like extracellular SOD
Correct answer: A. It oxidises Fe2+ to Fe3+, limiting hydroxyl radical formation
Explanation
Ceruloplasmin is a plasma copper-containing ferroxidase that converts Fe2+ to Fe3+. Because only the reduced ferrous form participates in the Fenton reaction generating hydroxyl radicals, keeping iron in the ferric state limits free radical production. Extracellular SOD is a separate distinct protein carrying copper, so option D confuses two different cuproproteins. Catalase performs peroxide decomposition intracellularly, not in plasma, eliminating option C.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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