Regulation of glucose-6-phosphate dehydrogenase. II. Resealed red cell ghosts

Resealed red cell ghosts were prepared at a final dilution of 1:325 from normal and G6PD-deficient cells. The activity of the HMS and concentrations of G6P, ATP, and total and reduced nictinamide adenine dinucleotide phosphate were determined after incubation in the presence of 0 and 100 micrometer methylene blue. The results indicate that the HMS is still under ununexplained restraint in the resealed cells but that the restraint has been reduced between twofold and fourfold from that observed in the intact normal red cells. The addition of various combinations of ATP, hexokinase, and methylene blue led to the demonstration that the unexplained restraint is not significantly correlated with levels of ATP or G6P. As with intact red cells, however, the explained restraint is greatest under conditions that cause the level of NADP+ to be low and that of NADPH to be high.