[Characteristics of two new mutant forms of erythrocyte glucose-6-phosphate dehydrogenase: "Kirovograd" G6PD and "Zhitomir" G6PD]. / Kharakteristika dvukh novykh mutantnykh form gliukozo-6-fosfatdegidrogenazy éritrotsitov: G6PD "Kirovograf" i G6PD "Zhitomir"

ABSTRACT

The paper comprises the description of properties of three mutant forms of glucoso-6-phosphate dehydrogenase characterized according the WHO program. Preparations of the enzymes were isolated from erythrocytes of patients with G6PD deficiency from three unrelated to one another Ashkenasi families coming from the Ukraine and from Byelorussia. Two new variants of G6PD hitherto never described in the literature were discovered. These variants were designated as "Kirovograd" and "Zhitomir" after the towns the probands came from. The properties of purified enzymes revealed by the methods of the WHO program were as follows the variant "Kirovograd" has a normal electrophoretic mobility in tris and TEB buffers and 98% of the normal in phosphate buffer. KM for G6P is 6,54; KM for NADP--2,19. It is characterized by a reduced thermostability and by an acute peak of activity at pH 8,5. The variant "Zhitomir" has 90-98% of the normal electrophoretic mobility in TEB buffer and 78-84% in phosphate buffer. KM for G6P is 5,4-8,3. KM for NADP is 1,4-3,1; with deoxyG6P is 50% and with deaminoNADP is 35%. It is also characterized with a reduced thermostability, while the curve of the dependence of its activity on pH has two peaks. Both variants are perfectly inactive with erythrocytes and thus should be assigned to the second group of the mutants variants of G6PD. The comparison of these variants to other variants encountered in the same national group revealed that they resemble certain quantitative variations.