Evidence for four types of erythrocyte glucose-6-phosphate dehydrogenase from G-6-PD-deficient human subjects.

Abstract

Glucose-6-phosphate dehydrogenase (G-6-PD) from the erythrocytes of 7 drug sensitive Negro males and 2 congenital nonspherocytic hemolytic anemia patients was isolated, purified and characterized in detail. Comparison of the G-6-PD from the deficient subjects confirmed the existence of 4 qualitatively different G-6-PD enzymes. G-6-PD from normal erythrocytes was characterized by a slow, type B, electrophoretic mobility, 2 Km values for glucose-6-phos-phate (G-6-P) (30-50 x 10-6 and 70-88 x 10-6 M), 4 Km values for nico-tinamide adenine dinucleotide phosphate (NADP) (1.7-2.3 x 10-6, 3.9-4.7 x 10-6, 6.6-8.4 x 10-6, and 12-15 x 10-6 m), 2 Km values for 2-deoxy-glucose-6-phosphate (2-dG[long dash]6-P, 9.71 x 10-3 and 2.5 x 10-3 m), 1 Km value for galactose-6-phosphate (Gal-6-P, 2.5 x 10-3m), and 2 activation energies (10 and 5 kilocalories/mole at 20-30[degree] C and 40-50[degree] C, respectively). Deficient type I was identical to the normal enzyme. Deficient type II was characterized by a fast, type A electrophoretic mobility, the lower Km value for G-6-P and NADP, the higher Km value for 2-dG-6-P, no activity towards Gal-6-P, and the activation energies were reversed with respect to temperature. Deficient type III had a fast, type A, electrophoretic mobility, the lower Km values for G-6-P and NADP, the higher Km value for 2-dG-6-P, was active towards Gal-6-P, and had only the lower activation energy. Deficient type IV from the congenital nonspherocytic hemolytic anemia patients had a fast, type A, electrophoretic mobility, the higher Km value for G-6-P, NADP, Gal-6-P and 2-dG-6-P, and the higher activation energy. G-6-PD deficiency in human erythrocytes may be produced by either quantitative or qualitative enzyme abnormalities.