Purification and properties of an abrnomal glutathione reductace from human erythrocytes

Abstract

1. 1. Glutathione reductase (NAD(P)H: oxidized glutathione oxidoreductase, EC 1.6.4.2) from the erythrocytes of a patient with a decreased activity of the enzyme was purified 10 000 times (specific activity, 20 μmoles NADPH oxidized per min per mg protein) by column chromatography; estimated purity, 10%. 2. 2. The Km values of GSSG and NADPH were practically the same as those for the normal enzyme. The influence of ions on the reaction velocity and the pH optimum were identical with the normal enzyme. 3. 3. The Kass value for FAD binding to the apoprotein was diminished. 4. 4. Consequently FAD protected the enzyme against denaturation during heating at 55° and diminished the losses during purification. Incubation of the holoenzyme with FMN decreased the activity.