Allelic expression in intergeneric fox hybrids (Alopex lagopus × Vulpes vulpes). II. Erythrocyte glucose-6-phosphate dehydrogenase in arctic and silver foxes: Purification and properties

Abstract

The functional properties of purified glucose-6-phosphate dehydrogenase (G6PD) from the erythrocytes of Arctic foxes (Alopex lagopus) and silver foxes (Vulpes vulpes) were investigated. It was found that pH optima for G6PD range from 8.15 to 8.25 in Arctic foxes and from 10.2 to 10.4 in silver foxes. For G6P, the estimated K _m values were 74×10⁻⁶ m (at pH 8.2) and 166×10⁻⁶ m (at pH 10.2) in Arctic foxes and 58×10⁻⁶ m (at pH 10.2) and 40×10⁻⁶ m (at pH 8.2) in silver foxes. The K _m values for NADP were estimated as 62×10⁻⁶ m (at pH 8.2) and 86×10⁻⁶ m (at pH 10.2) in the Arctic foxes and 15×10⁻⁶ m (at pH 10.2) and 12×10⁻⁶ m (at pH 8.2) in the silver foxes. It was found that Mg²⁺ ions exert a significant activating effect on G6PD in the Arctic fox and do not affect appreciably its activity in the silver fox. The experimental data indicate that slight differences in the electrophoretic mobility of G6PD are associated with considerable functional differences in this enzyme between the two fox species.