Erythrocyte Glutathione Reductase By ERNEST BEUTLER AND MARY

By ERNEST BEUTLER AND MARY K. Y. Yu m T HE EXACT ROLE of reduced glutathione ( OSH ) in the economy of the red blood cell remains to be defined. Drug-induced hemolytic anemia due to glucose-6-phosphate dehydrogenase deficiency is associated with lowt and with unstable2 0S1-I. Yet, a condition has been described in which red cell glutathione is virtually absent with only mild hemolysis being observed, and destruction of red cell glutathione by N-ethyl-maleimide does not appear to seriously impair red blood survival.4 The enzyme which is required to maintain glutathione in the reduced state is glutathione reductase. This enzyme normally transfers reducing power from the coenzyme TPNH to oxidized glutathione ( GSSG ) and thus restores this compound to the reduced form, GSH. Recently, it has been found that deficiency of glutathione reductase may be associated with sensitivity to drug-induced hemolysis5 and with nonspherocytic congenital hemoiytic anemia.#{176} The enzyme glutathione reductase was originally characterized in animal tissues by Rail and Lehninger,7 who assayed it in various rat tissues and found it to be TPN specific. More recently, LangdonS succeeded in preparing highly purified 0550 reductase from rat liver, and confirmed the absolute specificity of this enzyme for TPN. Racker, on the other hand, found that glutathione reductase from yeast and beef liver could catalyze hydrogen transfer from both DPNH and TPNH, but more rapidly with the latter.9 Francoeur and Denstedt1#{176} assayed crude human red cell preparations for OSSO-reductase activity and found that both TPN and DPN were effective as coenzymes. This observation has been confirmed by Carson et al.” The present studies have been carried out to determine (1) whether the DPNand TPN-active glutathione reductase activity of human red cells is due to a single enzyme or whether two enzymes, each with a different coenzyme specificity, could be separated; (2) whether the DPN-active enzyme of red cells could be harnessed to reduce oxidized glutathione (OSSO) in the intact erythrocyte. At the same time, it has been possible to characterize the enzyme glutathione reductase in relatively purified preparations.