The stereospecificity of glutathione reductase for pyridine nucleotides.

Crystalline glutathione reductase, prepared from yeast (3) was a generous gift from Dr. E. Backer. The enzyme had a specific activity of 8.8 units (pmoles of TPNH oxidized per minute) per mg of protein, after lyophilization, but had lost approximately three-fourths of this activity when it was used in the experiments here described. Another preparation of glutathione reductase was obtained from Eschwichti coli according to the procedure described by Asnis (4). The final product had a specific activity of 1.4 units per mg of protein, in which units are defined as above, but the assay system was that described by Asnis (4). GSSG was a product of Schwartz Laboratories. All other materials and procedures are described in the preceding papers (5,6).