“…Pyruvate kinase type I, which may play an important role in the control of glycolysis and gluconeogenesis, exhibits sigmoidal kinetics with phosphoenolpyruvate, allosteric activation with fructose 1,6-diphosphate and inhibi-tionbyATP (Taylor & Bailey, 1967;Carminatti etal., 1968;Susor & Rutter, 1968;Tanaka et al, 1967b). Whereas fructose 1,6-diphosphate or lower pH transforms the sigmoidal response to phosphoenolpyruvate into a hyperbolic relationship, they increase the co-operativity of the ATP inhibition (Tanaka et al, 1967b;Rozengurt et al, 1969). Inhibition by L-alanine resembles that of ATP (Llorente et al, 1970).…”