Ceruloplasmin, the copper-containing plasma protein, contributes to antioxidant defence through which specific activity?

• A Superoxide dismutation in plasma
• B Scavenging hydroxyl radicals directly
• C Reduction of lipid hydroperoxides using selenium
• D Ferroxidase activity converting Fe2+ to Fe3+, limiting Fenton chemistry ✓

Explanation

Ceruloplasmin functions as a multicopper ferroxidase, oxidising Fe2+ to Fe3+ for loading onto transferrin. By keeping circulating iron in the ferric state it minimises free Fe2+, the catalyst of the Fenton reaction that generates hydroxyl radicals. No extracellular superoxide dismutase function is attributed to ceruloplasmin, and hydroxyl radicals react too indiscriminately to be scavenged by any protein, killing options A and B.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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