[Nonphysiological redox-agents are reduced at the binding center of NADP(H) glutathione reductase].
Studies of the acceptor reductase reaction of yeast glutathione reductase (EC 1.6.4.2) revealed that the competitive inhibitors for NADPH, 2',5'-ADP and Br- decrease the rate constants for the enzyme oxidation by ferricyanide, phenanthrene quinone, and juglone. A similar effect is observed when NADH which does not bind to the reduced enzyme is used as substrate. These observations support the hypothesis that non-physiological redox agents are reduced at the NADP(H)-binding center of glutathione reductase and that NADP(H) binding stimulates the reaction by displacing tyrosine-197 which protects FAD from the solvent.
Bironaĭte
D A
DA
Chenas
N K
NK
Kulis
Iu Iu
IuIu
D001665:Binding Sites; D005292:Ferricyanides / Q000737:chemistry; D005980:Glutathione Reductase / Q000378:metabolism*; D007202:Indicators and Reagents; D009249:NADP / Q000378:metabolism*; D009285:Naphthoquinones / Q000737:chemistry; D010084:Oxidation-Reduction; D010616:Phenanthrenes / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000201:enzymology
D005292:Ferricyanides; D007202:Indicators and Reagents; D009285:Naphthoquinones; D010616:Phenanthrenes; C007931:hexacyanoferrate III; C005399:9,10-phenanthrenequinone; D009249:NADP; D005980:Glutathione Reductase; C005134:juglone