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Saturday 4 February 2006

- O2 is converted to superoxide (O2-) by oxidative enzymes in the endoplasmic reticulum (ER), mitochondria, plasma membrane, peroxisomes, and cytosol.

- O2- is converted to H2O2 by dismutation and thence to OH by the Cu2+/Fe2+-catalyzed Fenton reaction. H2O2 is also derived directly from oxidases in peroxisomes.

Resultant free radical damage to lipid (peroxidation), proteins, and DNA leads to various forms of cell injury.

02- superoxide catalyzes the reduction of Fe3+ to Fe2+, thus enhancing OH generation by the Fenton reaction. The major antioxidant enzymes are superoxide dismutase (SOD1), catalase, and glutathione peroxidase.

See also

- ocydative stress
- reactive oxygen species (ROS)


- Salvemini D, Cuzzocrea S: Superoxide, superoxide dismutase and ischemic injury. Curr Opin Investig Drugs 3:886, 2002.