title: The inhibition kinetics of yeast glutathione reductase by some metal ions.
abstract: Glutathione reductase (GR, type IV, Baker's yeast, E.C 1.6.4.2) is a flavoprotein that catalyzes the NADPH-dependent reduction of oxidized glutathione (GSSG) to reduced glutathione (GSH). In this study some metal ions have been tested on GR; lithium, manganese, molybdate, aluminium, barium, zinc, calcium, cadmium and nickel. Cadmium, nickel and calcium showed a good to moderate inhibitory effect on yeast GR. GR is inhibited non-competitively by Zn2+ (up to 2 mM) and activated above this concentration. Ca2+ inhibition was non-competitive with respect to GSSG and uncompetitive with respect to NADPH. Nickel inhibition was competitive with respect to GSSG and uncompetitive with respect to NADPH. The inhibition constants for these metals on GR were determined. The chelating agent EDTA recovered 90% of the GR activity inhibited by these metals.
authors.affiliation: Hacettepe University, Faculty of Medicine, Department of Biochemistry, 06100 Ankara, Turkey.
authors.forename: Berivan
authors.initials: B
authors.lastname: Tandoğan
authors.forename: N Nuray
authors.initials: NN
authors.lastname: Ulusu
mesh_terms: D001667:Binding, Competitive; D002118:Calcium / Q000737:chemistry; D002384:Catalysis; D004492:Edetic Acid / Q000737:chemistry; D005656:Fungal Proteins / Q000737:chemistry*; D005978:Glutathione / Q000737:chemistry; D005980:Glutathione Reductase / Q000737:chemistry*; D007477:Ions / Q000737:chemistry*; D007700:Kinetics; D008670:Metals / Q000737:chemistry*; D008956:Models, Chemical; D009249:NADP / Q000737:chemistry; D009532:Nickel / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000378:metabolism; D015032:Zinc / Q000737:chemistry
chemical_list: D005656:Fungal Proteins; D007477:Ions; D008670:Metals; D009249:NADP; D009532:Nickel; D004492:Edetic Acid; D005980:Glutathione Reductase; D005978:Glutathione; D015032:Zinc; D002118:Calcium