[Optimized determination and properties of NADPH-dependent glutathione reductase in serum. Studies on serum glutathione reductase, I. (author's transl)].
Reaction conditions were optimized for the determination of serum glutathione reductase, which has not yet been investigated systematically. Imidazole was found to be the most suitable buffer material; the highest glutathione reductase activity in serum was always obtained with imidazole/HCl buffer, which, in contrast to all other tested buffers, also resulted in the maximal enzyme activity without preincubation. In imidazole buffer, the pH-activity curve of serum glutathione reductase shows a broad optimum between pH 6.5 and 6.9. A GSSG concentration of 2 mmol/l and a NADPH concentration of 0.43 mmol/l gave maximal enzyme activity and a linear reaction over 10 min up to 20 U/l test solution. An investigation of serum glutathione reductase activity from 100 clinically healthy probands gave values between 20 and 50 U/l. In the optimized assay system the glutathione reductase in the serum reacts specifically with GSSG and NADPH.
D001322:Autoanalysis; D002021:Buffers; D004492:Edetic Acid; D005033:Ethylmaleimide / Q000494:pharmacology; D005980:Glutathione Reductase / Q000037:antagonists & inhibitors / Q000097:blood*; D006461:Hemolysis; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007093:Imidazoles; D009249:NADP; D013439:Sulfhydryl Reagents / Q000494:pharmacology; D015032:Zinc / Q000494:pharmacology
D002021:Buffers; D007093:Imidazoles; D013439:Sulfhydryl Reagents; D009249:NADP; D004492:Edetic Acid; D005980:Glutathione Reductase; D015032:Zinc; D005033:Ethylmaleimide
Optimierte Bestimmung und Eigenschaften der NADPH-abhängigen Glutathion-Reduktase im Serum. Untersuchungen über die Glutathion-Reduktase im Serum, I. Mitteilung