Inhibition of Adenosine Triphosphatase in Sheep Red Cell Membranes by Oxidized Glutathione |
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Authors: | D. A. T. Dick E. G. Dick D. C. Tosteson |
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Affiliation: | From the Department of Physiology and Pharmacology, Duke University Medical Center, Durham, North Carolina 27706. |
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Abstract: | This paper reports inhibition of Na+ + K+-stimulated, ouabain-inhibited adenosine triphosphatase (S-ATPase) in sheep red cell membranes by oxidized glutathione (GSSG). The results are consistent with the hypothesis that this inhibition depends upon the formation of a mixed disulfide between glutathione and -SH group(s) in the enzyme protein. Thus, inhibition of S-ATPase by GSSG proceeds more rapidly at alkaline than at neutral pH and is reversed by the addition of an excess of a compound containing reduced -SH groups (e.g. dithiothreitol). ATP protects S-ATPase against inhibition by GSSG and this protection depends on both the monovalent and divalent cation composition of the medium. Protection by ATP is more complete in the presence of K+ than in the presence of Na+. |
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