Heat flux and metabolic dynamics

The use of microcalorimetry as a complementary method to study regulation and control of metabolic fluxes has great potential, since microcalorimetry with a high precision measures an average of all metabolic fluxes rather than the time dependence of the concentration of specific metabolic intermediates. It is therefore possible to use microcalorimetry as an accurate fluxmeter for studies of metabolic dynamics [63]. 

This will be illustrated in the following example. Sustained oscillations of glycolytic intermediates have been shown in the yeast S. cerevisiae, both in cell free extracts [64, 65] and in whole cell cultures [63, 66]. Oscillatory growth is also a well-documented phenomenon in this yeast (see reference [16]) for further references). In the latter case, there may be an oscillatory shift in proportion of the respiratory and fermentative catabolism, during continuous aerobic growth on glucose. The oscillatory behaviour has been documented as an oscillation of substrate consumption rates and product formation rates rather than as an oscillation of metabolic intermediates [16]. An oscillatory behaviour may be of short (duration less than 1 min. [62, 63, 66]), medium (duration less than 1 hour [64]), or long term duration (duration of several days [16] ). 

Glycolytic oscillations in yeast have been known for a long time (for review see reference [67]). The fact that sustained oscillations can be observed in a population, implies that some synchronisation mechanisms prevents the cells 

The main obstacle to making calorimetric investigations on glycolytic oscillations is that it requires an instrument which is at the same time highly sensitive but also allows for rapid measurements since the time period of the 

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