Mouse-liver glutathione reductase: inactivation by NADPH or two allelic variants

Mouse-liver glutathione reductase has been purified to homogeneity from strain SWR/J by ammonium sulfate precipitation (40-80%) and two additional steps of affinity chromatography in ATPR-Sepharose and 2', 5'-ADP-Sepharose from which it was specifically eluted by using NADP+ gradients. After 2032-fold purification the pure enzyme has a specific activity of 146 U/mg. The SWR/J protein is slightly more basic than the other allelic variant from strain DBA/2J, with PI 7.0 and 6.5 respectively. Both pure proteins are immunologically identical, either by immunodiffusion or by quantitative immunoprecipitation, They can however be distinguished by their rate of inactivation in the presence of NADPH, their reduced cofactor. The SWR/J protein is much more resistant to that inactivation (t1/2 = 14 min) than the DBA/2J enzyme (t1/2 = 5 min).