Analysis of transport system for glutathione and glutathione conjugates as a factor of cell defense and drug metabolism.

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We have purified and characterized a novel ATPase in human erytlirocyLes which is stimulated by glutathione S-conjugate. Erythrocyte plasma membranes were prepared and solubilized into Triton-X 100, and applied on an affinity chromatography of S-hexylglutathione-Sepharose 6B. An protein fraction eluted by approximately 1.5 mM S-hexylglutathione was found to show ATPase activity stimulated by S-(2, 4-dinitrophenyl)glutathione(GS-DNP). An apparte Km of the enzyme was 38 mu H for GS-DNP, and 140 mu H for ATP. This enzyme protein reconstituted into phospholipid vesicles showed both GS-DUP-stimulated mg^<2+> -ATPase and tile GS-DNP transport activity. T he enzyme activity was stimulated by other glutatlilone S-co-niugates, and not inhibited by vanadate nor EGTA, suggesting that this is different from Na^+, K^+ -ATPase or Ca^<2+> -ATPase. Immunological study using a specific antisera against this enzyme showed that this enzyme presents in membranes of platelets, leukocytes, hepatocytes, as well as erythrocytes. These results suggest that GS-DNP-stimulated ATPase functions in the active transport of glutathione S-conjugates and cell defense system against oxidative stress.