ABSTRACT
The purified protein appears distinct, on the basis of catalytic and chromatographic behavior, from any previously known glutathione peroxidase and glutathione transferase. Proton-induced X-ray fluorescence analysis carried out on the purified enzyme showed the presence of one selenium atom per molecule. In order to determine the enzymatic activity spectrophotometrically, particularly when the specific activity is very low, the use of a detergent in order to stimulate the activity and of a cuvette equipped with a magnetic stirrer is mandatory. The phospholipid hydroperoxide glutathione peroxidase (PHGPX) was purified following the glutathione-dependent peroxidation-preventing activity present in the cytosol. By preventing the free radical generation from lipid hydroperoxides, PHGPX would reduce the vitamin E requirement necessary to inhibit peroxidation. The enzyme PHGPX seems to play a fundamental role in the protection of the membranes of living tissues from lipid peroxidation, as suggested also by the observation that the major product of lipid peroxidation in vivo is the hydroxy derivative or phospholipid.
