SUPEROXIDE RADICALS, SUPEROXIDE DISMUTASES AND THE AEROBIC LIFESTYLE

Abstract— The superoxide radical (O^-₂) is a commonplace product of the biological reduction of molecular oxygen and plays an important role in oxygen toxicity. Superoxide dismutases (SOD) catalytically scavenge this radical and are the primary defense against its cytotoxicity. The data which support these statements have been briefly reviewed. Oxygen enhances the lethality of certain antibiotics, such as streptonigrin, and of ionizing radiation as well. The role of O^-₂ in the enhancements is presented and the basis of the radioprotective effects of SOD discussed. Several more recent developments are presented in detail including: (a) The induction of the MnSOD of E. coli upon exposure to very low levels of oxygen, (b) The changes in SOD in E. coli as a function of nutritional state, during culture in a chemostat. (c) A convenient new assay and activity stain for SOD.