Which enzyme is the primary intracellular defense against superoxide anion (O2•−) in cells?

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

Explanation

Superoxide dismutase (SOD) catalyzes the dismutation of superoxide anion into hydrogen peroxide and molecular oxygen, serving as the primary enzymatic defense against superoxide. Catalase and glutathione peroxidase act on hydrogen peroxide, not superoxide. Myeloperoxidase generates hypochlorous acid from hydrogen peroxide in neutrophils and is not a free radical scavenger.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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