Purification of glutathione-binding proteins from bovine milk and identification of glutathione S-transferase

Summary

Glutathione is both a ubiquitous and abundant antioxidant in tissues and fluids, and critical as reducing substrate for several enzymes. Particularly, glutathione is utilized by important enzymes, such as glutathione peroxidase (GPx) and glutathione S-transferase (GST). The importance of these glutathione-utilizing enzymes for the oxidative stability of milk is, however, unclear. We have purified glutathione-binding proteins from bovine milk using glutathione-affinity chromatography and report as a novel observation the identification of GST m as a major glutathione-binding protein in bovine milk. GPx was not purified by the glutathione-affinity column.