A patient with Wilson's disease (hepatolenticular degeneration) has decreased serum ceruloplasmin and elevated free serum copper. Ceruloplasmin's primary biochemical function, beyond copper transport, involves which antioxidant enzyme activity?

• A Superoxide dismutase activity, converting O2- to H2O2
• B Catalase activity, converting H2O2 to H2O and O2
• C Glutathione peroxidase activity, using selenium to reduce lipid peroxides
• D Ferroxidase activity, oxidising Fe2+ to Fe3+ for transferrin loading ✓

Explanation

Ceruloplasmin contains 6-7 copper atoms per molecule and has ferroxidase I activity — it oxidises ferrous iron (Fe2+) to ferric iron (Fe3+), enabling iron to be loaded onto transferrin for plasma transport. Fe2+ (Fenton reaction substrate) would otherwise generate hydroxyl radicals (OH•) from H2O2 via Fe2+ + H2O2 → Fe3+ + OH• + OH-. By converting Fe2+ to Fe3+, ceruloplasmin prevents Fenton chemistry and limits iron-mediated oxidative stress. In Wilson's disease, free copper itself promotes oxidative damage. Ceruloplasmin also has weaker superoxide dismutase-like activity but ferroxidase is its primary antioxidant/iron metabolism role.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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