Negro Variant of Glucose-6-Phosphate Dehydrogenase Deficiency (A - ) in Man

Abstract

Glucose-6-phosphate dehydrogenase in erythrocytes of the Negro type associated with enzyme deficiency (A^-) was separated by chromatography on a carboxymethyl-Sephadex column from the electrophoretically indistinguishable Negro variant with normal enzyme activity (A⁺). Quantitative immunologic neutralization tests indicated that the A^- enzyme had about the same enzymatic and serological activity as the A⁺ and the normal (B⁺) enzymes. The enzyme activity of the A^- variant in young erythrocytes was similar to that in young cells from normal individuals, although the activity of the A^- variant in unfractionated red cells was 10 to 15 percent of normal. These data indicate that the basic defect in the variant enzyme (A^-) is a structural mutation which causes more rapid degradation of the enzyme during erythrocyte aging.