Studies on glutathione S-transferase, glutathione peroxidase and glutathione reductase in human normal and cataractous lenses.

The cause(s) for decreased reduced glutathione (GSH) content of human senile cataracts were investigated by determination of three enzymes of GSH metabolism: GSH S-transferase, GSH peroxidase and GSH reductase. There are significant decreases in activities of GSH S-transferase of early cataracts (-76%) and of dark advanced cataracts (-73%) as compared to clear age-matched lenses. However, the activities of GSH peroxidase were only slightly decreased in cataracts as compared to clear age-matched lenses. The decrease in enzymes of GSH metabolism does not account for increased GSH degradation. Thus decreased GSH synthesis and leak out from cataractous lenses may account for the GSH loss in cataracts.