Mediterranean glucose 6‐phosphate dehydrogenase (G6PD) deficiency – Near normal decay of the mutant enzyme protein in circulating erythrocytes

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Abstract
Complete removal of leukocytes and platelets from erythrocytes and the development of a sensitized procedure for the assay of G6PD [glucose-6-phosphate dehydrogenase] activity allowed the biochemical mechanisms of the Mediterranean variety of G6PD deficiency to be re-evaluated. Activity in the young erythrocytes from 9 G6PD-deficient subjects averaged 0.1% of the levels observed in the corresponding erythrocyte fraction from normal individuals: moreover, the decline of activity during aging of the G6PD-deficient erythrocytes was comparable with that observed for the normal enzyme. Mutant G6PD purified from granulocytes of a G6PD-deficient subject and entrapped within the corresponding erythrocytes was remarkably stable. Exposure of native erythrocytes to an oxidative stress (divicine plus ascorbate) resulted in a decrease of G6PD activity that was significantly more rapid and expensive in control than in G6PD-deficient cells. Enhanced intracellular breakdown of the mutant protein within the circulating erythrocytes was excluded.