Déficit en congénital pyruvate kinase érythrocytaire: Étude cinétique de l'enzyme et conséquences métaboliques

Abstract

In nine anaemic patients with erythrocyte pyruvate kinase deficiency and six healthy related subjects with the same deficiency, the red cells' glycolytic changes have been analysed. In patients with haemolytic anemia, ATP level is clearly lowered, mono- and diphosphoglycerates are very increased, glycolysis rate is nearly normal. The effect of deficiency upon glycolytic regulation is discussed. Kinetic studies of partially purified enzyme were performed in twelve cases with the defect. In nine cases, kinetic characteristics were normal: the enzyme is an allosteric one, the activity of which is increased during storage at + 4°C. With fructose diphosphate the half activity of phosphoenol pyruvate ( K 1 2 PEP) is recovered at the constant concentration of 3 · 10 −5 M. In one case, K 1 2 PEP was very increased but the enzyme was always very sensitive to fructose diphosphate activation. In another deficient family, mother and daughter's pyruvate kinase were characterised by the absence of response to fructose diphosphate or its diminution. This ester changes neither K 1 2 PEP nor the Hill interaction coefficient. It cannot be concluded that a structural anomaly is responsible for these kinetic modifications.