Membrane thiol-disulfide status in glucose-6-phosphate dehydrogenase deficient red cells. Relationship to cellular glutathione.

The behavior of glucose-6-phosphate dehydrogenase (G6PD)-deficient red cell membrane proteins upon treatment with diamide, the thiol-oxidizing agent (Kosower, N.S. et al. (1969) Biochem. Biophys. Res. Commun. 37, 593-596), was studied with the aid of monobromobimane, a fluorescent labeling agent (Kosower, N.S., Kosower, E.M., Newton, G.L. and Ranney, H.M. (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 3382-3386) convenient for following membrane thiol group status. In diamide-treated G6PD-deficient red cells (and in glucose deprived normal cells), glutathione (GSH) is oxidized to glutathione disulfide (GSSG). When cellular GSH is absent, membrane protein thiols are oxidized with the formation of intrachain and interchain disulfides. Differences in sensitivity to oxidation are found among membrane thiols. In diamide-treated normal red cells, GSH is regenerated in the presence of glucose and membrane disulfides reduced. In G6PD-deficient cells, GSSG is not reduced, and the oxidative damage (disulfide formation) in the membrane not repaired. Reduction of membrane disulfides does occur after the addition of GSH to these membranes. A direct link between the thiol status of the cell membrane and cellular GSH is thereby established. GSH serves as a reductant of membrane protein disulfides, in addition to averting membrane thiol oxidation.