Superoxide generated during reperfusion undergoes dismutation to hydrogen peroxide. In the presence of iron, hydrogen peroxide is converted to the hydroxyl radical by which reaction?

• A Haber-Weiss reaction, catalyzed by iron (Fenton chemistry) ✓
• B Glutathione peroxidase reaction using reduced glutathione
• C Nitric oxide synthase reaction generating peroxynitrite
• D Xanthine oxidase reaction converting hypoxanthine to uric acid

Explanation

Hydrogen peroxide reacts with ferrous iron in the Fenton reaction to yield hydroxyl radicals and hydroxide ions; superoxide can reduce ferric iron back to the ferrous form so the two reactions together constitute the iron-catalyzed Haber-Weiss reaction. Glutathione peroxidase detoxifies hydrogen peroxide and therefore opposes this process. Peroxynitrite arises from nitric oxide plus superoxide, and xanthine oxidase generates superoxide upstream rather than converting hydrogen peroxide to hydroxyl radical.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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