INHIBITION OF LIPID AUTOXIDATION BY BOVINE SUPEROXIDE-DISMUTASE

For autoxidation, the initiation reactions, which are believed to be responsible for the formation of hydroxyl radicals, are inhibited by superoxide dismutase (SOD). Soybean lipoxygenase types I, IV and V were not inhibited by SOD in model systems containing linoleic acid. Autoxidation in a low-iron model system was further reduced by SOD. Autoxidation in the presence of haemin was rapid but also inhibited by SOD. These observations indicate that SOD mainly prevents the formation of hydroxyl radicals via the Haber-Weiss reaction during the iron-catalysed oxidation of linoleic acid, although it is possible that the enzyme might also inhibit haemin-catalysed oxidation by scavenging an oxy-haem complex.