Experimental observations on glycolytic oscillations

Glycolytic oscillations are the prototype for periodic phenomena in biochemistry, even if the function of these oscillations, if there is any, has for long remained obscure. Their study began some 30 years ago, and still continues. The first observation indicating the existence of oscillatory behaviour in glycolysis is due to Duysens Amesz (1957), who reported, by studying the fluorescence of some glycolytic intermediates in yeast, that one of these underwent damped oscillations in the course of time (fig. 2.1). 

1965 Betz Moore, 1967 Betz Sel kov, 1969 Hess et al, 1969) or following changes in pH (Hess et al., 1969 Hocker et al, 1994). Yeast cells undergoing glycolytic oscillations rapidly synchronize in stirred suspensions (Ghosh, Chance Pye, 1971). The synchronizing factor 

Input rate m h Period (min) Amplitude in mMNADH Damping Waveform 

The essential property of glycolytic oscillations is illustrated by fig. 2.4a and b as well as table 2.1 sustained periodic behaviour is observed only in a precise range of substrate injection rates. This observation, carried out in yeast extracts (Hess Boiteux, 1968b, 1973 Hess et al, 1969), was confirmed (Von Klitzing Betz, 1970) in suspensions of intact yeast cells (fig. 2.5). Below a critical value of the substrate injection rate, the system reaches a stable steady state. When this rate increases, oscillations occur, but they disappear when the substrate injection rate exceeds a second, higher, critical value. This disappearance is reversible, as shown by fig. 2.4b. The period of glycolytic oscillations is of the order of several minutes and diminishes as the substrate injection rate increases (Hess et al, 1969 Hess Boiteux, 1973 see table 2.1). 

The control by the substrate injection rate of the period, amplitude and very existence of glycolytic oscillations makes these a particularly appropriate model for the study of biological rhythms. Moreover, in contrast with many of these rhythms for which the mechanism of oscillations remains obscure, the molecular basis of glycolytic oscillations is known. This allows the construction of realistic models, which in turn 

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