Allosteric activation of human erythrocyte pyruvate kinase by fructose-1,6-diphosphate: Kinetic and equilibrium binding studies

Abstract

Summary Fructose-1,6-diphosphate activation of human erythrocyte pyruvate kinase was studied at various phosphoenolpyruvate concentrations. Kinetic data show that, as phosphoenolpyruvate concentration increases, K 1/2 value and cooperativity for fructose-1,6-diphosphate decrease. Equilibrium dialysis experiments, performed with radioactive fructose-1,6-diphosphate show that phosphoenolpyruvate enhances fructose-1,6-diphosphate binding. In the two types of experiments, fructose-1,6-diphosphate concentrations are of the same order of magnitude (10−7 M). The kinetic and equilibrium binding data coincide with the erythrocyte concentrations.