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Reactive oxygen species clearance

Superoxide dismutases convert superoxide enzymatically into hydrogen peroxide, which can be converted into water either by the enzyme catalase or the enzyme glutathione peroxidase. In the glutathione peroxidase reaction, glutathione is oxidized to glutathione disulfide. Glutathione disulfide can be converted back to glutathione by glutathione reductase, in a reaction that consumes NADPH. Legend: H2O = water; H2O2 = hydrogen peroxide; O2 = oxygen molecule; O2.- = superoxide; GSH = glutathione; GSSH = glutathione disulfide (oxidized form of glutathione); NADP+ = nicotinamide adenine dinucleotide phosphate; NADPH = nicotinamide adenine dinucleotide phosphate (reduced form). (Contributed by Dr. Douglas Lanska.)