OPTIMAL AND STABLE CONDITIONS FOR THE DETERMINATION OF ERYTHROCYTE GLUTATHIONE-REDUCTASE ACTIVATION COEFFICIENT TO EVALUATE RIBOFLAVIN STATUS

To measure the activation coefficient (AC) of erythrocyte glutathione reductase (GR), suspended whole blood was lysed in a preincubation sol ution, with or without 100 mu M flavin adenine dinucleotide (FAD). Upo n addition of the reaction mixture, FAD concentration decreased about 10-fold. No AC values <1 were obtained in arty of the subjects. The ra nge of unstimulated activity per g hemoglobin (Hb) was 5 to 12 U. AC v alues of healthy subjects (1.3) decreased to about 1.15 after vitamin supplementation of 1 RDA for 3 wk. In healthy young subjects consumpti on of dietary riboflavin at levels as low as 0.5 mg/d resulted in an A C of 1.6.