Which antioxidant enzyme catalyzes the dismutation of cytotoxic superoxide free radicals (O2•-) into molecular oxygen and hydrogen peroxide?
Answer and explanation
Correct answer: B. Superoxide dismutase (SOD)
Superoxide dismutase (SOD) contains metal cofactors (Cu/Zn-SOD in cytosol, Mn-SOD in mitochondria) and catalyzes the reaction: 2 O2•- + 2 H+ -> O2 + H2O2. The resulting hydrogen peroxide is subsequently degraded into water and oxygen by catalase and glutathione peroxidase, protecting cells from reactive oxygen species (ROS).
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