Glutathione peroxidase decomposes superoxide

Spin trapping has been widely used for superoxide detection in various in vitro systems [16] this method was applied for the study of microsomal reduction of nitro compounds [17], microsomal lipid peroxidation [18], xanthine-xanthine oxidase system [19], etc. As DMPO-OOH adduct quickly decomposes yielding DMPO-OH, the latter is frequently used for the measurement of superoxide formation. (Discrimination between spin trapping of superoxide and hydroxyl radicals by DMPO can be performed by the application of hydroxyl radical scavengers, see below.) For example, Mansbach et al. [20] showed that the incubation of cultured enterocytes with menadione or nitrazepam in the presence of DMPO resulted in the formation of DMPO OH signal, which supposedly originated from the reduction of DMPO OOH adduct by glutathione peroxidase. 

Free radicals participate in a wide variety of chemical reactions. The most significant radicals in the human body are the superoxide radical (O2") and the hydroxyl radical (OH ). These radicals cause the oxidative damage of biomolecules. Substances eliminating free radicals can be used to prevent these harmful processes. Free radicals can be decomposed enzymatically superoxide dismutase, glutathione peroxidase and catalase enzymes are the major players in this game. Superoxide dismutase catalyzes the following reaction ... 

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