[Identification of the inhibition type of hexokinase and pyruvate kinase activity by Ca2+]

Ca2+ inhibitory effect on hexokinase (HK) and pyruvatkinase activities is studied. Kinetic analysis of the inhibition reaction is carried out to determine the inhibition type. Non-competitive inhibition with respect to reaction activator, Mg2+, is found for HK and PK. On the basis of graph analysis data for both reactions the values of the activatory constant (KA) and the inhibitory constant (Ki) are calculated. The experimental results are discussed with respect to possible regulatory effect of Ca2+ on glycolysis cycle.