On the regulatory properties of the pyruvate kinase from Trypanosoma cruzi epimastigotes

Abstract

The pyruvate kinase from Trypanosoma cruzi epimastigotes was activated by fructose 2,6-diphosphate ((A) 0.5 = 0.17 μM), through a decrease in (S) 0.5 and an increase in Vmax for both substrates. The enzyme was 50% inhibited by 0.9 mM ATP or 0.5 mM Pi in the presence of 30 mM MgC12; these inhibitions were completely counteracted by 1.5 μM fructose 2,6-diphosphate. Both facts suggest that the effects are allosteric, and not due to chelation. © 1989.