Studies on glutathione transport utilizing inside-out vesicle prepared from human erythrocytes |
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Authors: | Takahito Kondo George L. Dale Ernest Beutler |
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Affiliation: | Department of Clinical Research, Scripps Clinic and Research Foundation, 10666 North Torrey Pines Road, La Jolla, CA 92037 U.S.A. |
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Abstract: | Adenosine triphosphate-dependent glutathione transport was characterized using inside-out vesicles made from human erythrocytes. Kinetic analysis of the glutathione disulfide (GSSG) transport showed a biphasic Line-weaver-Burk plot as a function of GSSG concentration suggesting the operation of two different processes. One phase had a high affinity for GSSG and a low transport velocity. Most active at acidic pH and at 25°C, this transport activity was easily lost during the storage of vesicles at 4°C. The for Mg-ATP was 0.63 mM; guanosine triphosphate (GTP) substituted for ATP gave a 340% stimulation of transport activity. Neither dithiothreitol nor thiol reagents affected this transport process. The other phase had a low affinity for GSSG and a high transport velocity. Most active at pH 7.2 and 37°C, this transport activity was stable during storage of vesicles at 4°C for several days. The for Mg-ATP was 1.25 mM; GTP substituted with no change in activity. Dithiothreitol increased the V but did not alter the , and thiol reagents inhibited the transport. These findings suggest that there are two independent transfer processes for GSSG in human erythrocytes. |
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Keywords: | Glutathione transport Inside-out vesicle (Human erythrocyte) GSH, reduced glutathione GSSG, oxidized glutathione |
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