Superoxide dismutase (SOD) catalyses the dismutation of superoxide radical. The reaction product that must then be removed by catalase or glutathione peroxidase is:
- A Hydrogen peroxide (H2O2) ✓
- B Hydroxyl radical (OH•)
- C Peroxynitrite (ONOO-)
- D Singlet oxygen (1O2)
Correct answer: A. Hydrogen peroxide (H2O2)
Explanation
SOD catalyses: 2 O2•− + 2H+ → H2O2 + O2. Hydrogen peroxide is still a reactive oxygen species capable of forming the highly toxic hydroxyl radical (via Fenton reaction: Fe2+ + H2O2 → Fe3+ + OH• + OH−). Catalase (2H2O2 → 2H2O + O2) and glutathione peroxidase (reduces H2O2 to H2O using reduced glutathione) complete the detoxification. Failure of this coordinated system contributes to oxidative stress in ischaemia-reperfusion injury.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.