Haemolytic Anaemia due to Glucose‐6‐Phosphate Dehydrogenase (G6PD) Deficiency: Demonstration of Two New Biochemical Variants, G6PD Hamm and G6PD Tarsus

Publisher Website
Google Scholar
Abstract
Summary. Two new variants of erythrocytic glucose‐6‐phosphate dehydrogenase have been found in one German patient and in another patient of Turkish origin. The enzymes were partially purified 165‐fold and 111‐fold respectively. Both revealed reduced activity, increased thermolability and a pH‐optimum in the alkaline region (8.5 and 9.0). One variant (G6PD Hamm) had a low Km‐value for glucose‐6‐phosphate, the other (G6PD Tarsus) exhibited an increased affinity for glucose‐6‐phosphate and a reduced affinity for NADP+. This enzyme showed an increased inhibitor constant for NADPH with respect to NADP+. Electrophoretic mobility was normal in both cases. 2‐Desoxy glucose‐6‐phosphate was utilized to an increased rate by both variant enzymes (46% and 33%). Also galactose‐6‐phosphate (29% and 25%) and deamino‐NADP+ (230% and 261%) gave increased utilization rates. The mothers of both patients could be identified as heterozygous for this enzyme deficiency.