Glutathione transferases: a possible role in the detoxication and repair of DNA and lipid hydroperoxides.

Two types of GSH peroxidase occur in the cell both of which detoxify fatty acid hydroperoxides, thymine hydroperoxide and DNA hydroperoxides. One is a Se-dependent enzyme which also detoxifies H2O2. The other contains members of the GSH transferase supergene family. These non-selenium dependent GSH peroxidases do not detoxify H2O2 and have substrate specificities varying markedly with the isoenzyme. Of particular interest is GSH transferase 5*-5* an enzyme extracted from the nucleus with urea which has a relatively high activity towards DNA hydroperoxide. The possible role of these enzymes in the detoxication of lipid and DNA hydroperoxides is discussed and it is pointed out that they may be important participants in mechanism for the repair of free-radical damage.