INACTIVATION OF GLUTATHIONE-REDUCTASE BY FENTON-SYSTEMS - METALLIC ION SPECIFICITY AND THE FUNCTION OF OXYGEN RADICALS

Yeast glutathione reductase (GR) was inactivated by Fenton Systems (FS ), Cu(II)/H2O2, Fe(II)/H2O2, Ni(II)/H2O2 and Co(II)/H2O2, being most e ffective. Ascorbate enhanced GR inactivation. The effect of Cu(II)/H2O 2 was relatively slow and depended on Cu(II) and H2O2 concentration. C atalase, serum albumin, benzoate (Na) and ethanol prevented GR inactiv ation. EDTA and DETAPAC protected GR but did not activate the inactiva te enzyme. L-Histidine protected GR or enhanced Cu(II)H2O2 effect, acc ording to its concentration. GR damage by Cu(II)H2O2 involved tryptoph an and tyrosine residues, as indicated by GR fluorescence. Cu(II)/NADP H (orNADH) system also inactivated GR, an effect depending on oxygen r adicals.