An isozyme of erythrocyte pyruvate kinase (PK-Los Angeles) with impaired kinetics corrected by fructose-1, 6-diphosphate.

A mutant isozyme of erythrocyte pyruvate kinase was found in a family of French-Canadian ancestry in association with hemolytic anemia. The isozyme was characterized by normal maximal activity, pH optimum, heat stability, and fructosediphosphate activation constants, but had markedly reduced affinity for the substrate, phosphoenolpyruvate. This kinetic defect was corrected almost entirely in vitro by low concentrations of fructosediphosphate.