Preparation of the L form of rabbit liver pyruvate kinase (EC 18.104.22.168) in the presence of fructose 1,6-diphosphate yielded an enzyme which was kinetically identical with the M or muscle-type form of pyruvate kinase found in liver. Chromatographic and dialysis studies of this complex showed that most of the fructose 1,6-diphosphate molecules were loosely bound to the enzyme, but dilution–dissociation studies and binding experiments established that there was a high initial affinity between the enzyme and fructose 1,6-diphosphate (Kassoc.+2.3×109), and that binding of the loosely bound fructose 1,6-diphosphate was concentration-dependent and a necessary condition to overcome the co-operative interaction observed with the homotropic effector phosphoenolpyruvate. Preparation of the liver enzyme in the absence of EDTA did not yield a predominantly M form of the enzyme, and incubation of the M form in the presence of EDTA did not convert it into the L form, but resulted in inhibition of enzyme activity. Immunological studies confirmed that the L and M forms in liver were distinct, and that preparation of the L form in the presence of fructose 1,6-diphosphate did not produce an enzyme antigenically different from the L form prepared in the absence of this heterotropic effector.
Studies on the interaction between rabbit liver pyruvate kinase and its allosteric effector fructose 1,6-diphosphate
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M. G. Irving, J. F. Williams; Studies on the interaction between rabbit liver pyruvate kinase and its allosteric effector fructose 1,6-diphosphate. Biochem J 1 February 1973; 131 (2): 303–313. doi: https://doi.org/10.1042/bj1310303
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