Which enzyme catalyzes the conversion of hydrogen peroxide to water using glutathione as the electron donor, thereby linking antioxidant defense to the hexose monophosphate shunt?

• A Catalase
• B Superoxide dismutase
• C Myeloperoxidase
• D Glutathione peroxidase ✓

Explanation

Glutathione peroxidase reduces hydrogen peroxide and lipid hydroperoxides to water and alcohols while oxidizing reduced glutathione (GSH) to GSSG. GSSG is regenerated to GSH by glutathione reductase using NADPH, whose principal source is the hexose monophosphate shunt. Catalase decomposes peroxide but does not use glutathione. Superoxide dismutase acts on superoxide, not peroxide. Myeloperoxidase generates hypochlorous acid in neutrophils and is a pro-oxidant enzyme.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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