Characterization of erythrocytic glucose-6-phosphate dehydrogenase in a mouse strain with reduced G6PD activity

Erythrocytic glucose-6-phosphate dehydrogenase (G6PD) of a mutant mouse strain with X-linked G6PD-deficiency was purified and compared with the wildtype G6PD by biochemical and physiological characteristics. The red cell G6PD activity of the mutant was 20% of the wildtype. The Michaelis constant (Km) of the substrate glucose-6-phosphate (G6P) was higher (90 microM) for the mutant than for the wildtype (56 microM). The isoelectric focusing with a pH range from 3 to 10 showed one more enzymatically active band for the wildtype G6PD compared to the mutant enzyme. Other enzyme characteristics, however, such as Km for nicotinamide adenine dinucleotide phosphate (NADP), utilisation of 2-deoxy-glucose-6-phosphate (2dG6P) and deamino-NADP, heat stability, pH optimum, molecular weight, and glucose metabolisation via the pentosephosphate pathway were similar in mutant and wildtype enzyme.