Purification and characterization of glutathione reductase from sheep liver

Glutathione reductase (Glutathione: NADP+ oxidoreductase, EC 1.8.1.7; GR) was purified from sheep liver. The purification included 4 steps: preparation of homogenate, ammonium sulfate fractionation, 2', 5'-ADP Sepharose-4B affinity chromatography, and gel filtration chromatography. GR was obtained with a yield of 14.1% having a specific activity of 47.27 EU/mg proteins. Optimal pH, stable pH, and optimal temperature were 8.0, 5.5, and 60 degrees C, respectively. K-M and V-max values for NADPH and GSSG substrates were 0.0258 and 0.0239 mM, and 0.266 and 0.255 EU/ml, respectively. The overall purification was about 1477-fold for liver GR. The enzyme activity was measured spectrophotometrically at 340 nm. In addition, K-j values of 4.367 and 0.4055 mM were determined by means of Lineweaver-Burk graphs for NADP(+) and GSH, respectively.