Abstract
Type and range of entrainment of glycolytic oscillations by a periodic source of substrate are determined experimentally in yeast extracts. Subharmonic entrainment proves the nonlinear nature of the glycolytic oscillator Random variation of the substrate input yields sustained oscillations of irregular waveform and stable period. The results agree with the predictions of an allosteric model for phosphofructokinase (EC 2.7.1.11; ATP:D-fructose-6-phosphate 1-phosphotransferase), which is the enzyme responsible for periodic operation of glycolysis. A comparison between model and experiment in the case of a constant source of substrate further indicates that the oscillatory dynamics of the glycolytic system can satisfactorily be described by the phosphofructokinase model.