On the molecular basis pyruvate kinase deficiency: I. Primary defect or consequence of increased glutathione disulfide concentration

Abstract

1. 1. Human erythrocyte pyruvate kinase (ATP:pyruvate phosphotransferase EC 2.7.1.40) can be converted into an oxidized form by incubation with oxidized glutathione. The oxidized enyzme can be reduced again by incubation with mercaptoethanol, with reduced glutathione a partial reduction of the enzyme is obtained. 2. 2. The oxidized enzyme shows a lower affinity for the substrate phosphoenol-pyruvate and for the allosteric effector fructose 1,6-diphosphate. The thermolability of the oxidized enzyme is markedly increased, compared with the freshly isolated or reduced enzyme. 3. 3. The data obtained with oxidized enzyme are discussed in relation to the data obtained with pyruvate kinase from pyruvate kinase-deficient patients. It is concluded that erythrocyte pyruvate kinase deficiency can be a consequence of an increased oxidized glutathione concentration in the red blood cell.