Electron Spin Resonance Investigations of Oxygen-Centered Free Radicals in Biological Systems
Oxygen-centered free radicals have been detected directly with ESR in a variety of biological processes such as lipid autoxidation,1 the enzymatic formation of superoxide by xanthine oxidase,2 and hydroxyl radical formation by the Y-irradiation of ice.3 Since the common isotope of oxygen is spin-less, no nuclear hyperfine interaction is possible, and the g-value and any hydrogen hyperfine coupling provide the only criteria for distinguishing an oxygen-centered free radical from other free radicals. The greatest limitation on the direct detection of oxygen-centered free radicals, aside from their high reactivity, is their paramagnetic properties.
KeywordsElectron Spin Resonance Xanthine Oxidase Hydroxyl Radical Scavenger Pulse Radiolysis Hydroxyl Radical Formation
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