Hydrogen peroxide generated during oxidative stress is converted to the highly reactive hydroxyl radical by a metal-catalyzed reaction. Which of the following correctly identifies this reaction and its required cofactor?
- A Fenton reaction requiring ferrous iron (Fe2+) or cuprous copper (Cu+) ✓
- B Haber-Weiss reaction catalyzed by ferric iron (Fe3+) alone
- C Superoxide dismutase reaction requiring manganese
- D Glutathione peroxidase reaction requiring vitamin C
Correct answer: A. Fenton reaction requiring ferrous iron (Fe2+) or cuprous copper (Cu+)
Explanation
The Fenton reaction converts hydrogen peroxide to the hydroxyl radical and hydroxide ion in the presence of ferrous iron or cuprous copper: Fe2+ + H2O2 gives Fe3+ plus OH radical plus OH-. Iron and copper are therefore dangerous catalysts of free radical injury in tissues. Option B is incorrect because the full Haber-Weiss sequence needs reduced metal generated by the Fenton step, and Fe3+ alone does not split hydrogen peroxide efficiently. SOD and glutathione peroxidase are protective antioxidant enzymes, not radical-generating reactions.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.