[Multiple forms of NADPH-dependent glutathione reductase in serum. Studies on the NADPH-dependent glutathione-reductase in serum II. (author's transl)].

Sera with elevated activities of glutathione reductase were investigated by gel electrophoresis in agar or polyacrylamide, and by gel filtration. In both separation methods the glutathione reductase activity in individual samples was resolved, showing up to three fractions differing in rate of migration and molecular size. The fractions with the lowest and highest molecular weight, corresponded respectively to the slowest and fastest migrating bands in agar gel electrophoresis. Preincubation of the serum samples with FAD or neuraminidase had no effect on the rate of migration of the three fractions. After the addition of beta-mercaptoethanol to the serum, gel electrophoresis and gel filtration showed only the enzyme fraction with the slowest rate of migration and the lowest molecular weight (140,000). The other two fractions reappeared after removal of the thiol from the serum. Further studies on the isolated (agar gel electrophoresis) fractions showed the existence of oligomeric forms of the enzyme, which are reversibly interconvertible.