PURIFICATION AND SOME PROPERTIES OF GLUTATHIONE-REDUCTASE FROM IRON-OXIDIZING BACTERIUM THIOBACILLUS-FERROOXIDANS

Glutathione reductase was purified from iron-grown Thiobacillus ferroo xidas AP19-3 to an electrophoretically homogeneous state. The enzyme h ad an apparent molecular weight of 100,000 and was composed of two ide ntical subunits of molecular weight (M,s, 52,000) as estimated by sodi um dodecyl sulfate-polyacrylamide gel electrophoresis. A purified enzy me reduced one mole of the oxidized form of glutathione (GSSG) with on e mole of NADPH to produce two moles of the reduced form of glutathion e (GSH) and one mole of NADP(+). The glutathione reductase was most ac tive at pH 6.5 and 40 degrees C, and had an isoelectric point at 5.1, The Michaelis constants: of glutathione reductase for GSSG, NADPH, and NADH were 300, 26, and 125 mu M, respectively.