EXPERIMENTAL-DATA ON THE ENERGETIC FLUX DURING GLYCOLYTIC OSCILLATIONS IN YEAST EXTRACTS

Calorimetric experiments were performed on yeast extracts in which gly colytic oscillations were occurring. High metabolic fluxes coincided w ith low amplitudes and with high frequencies in a temperature range fr om 283 to 303 K, yielding an activation energy of E(a) = 76.8 kJ mol(- 1) and a mean Q(10) value of 2.5 +/- 0.4. The calorimetrically determi ned reaction enthalpy Delta(f)H(0,) of the glycolytic catabolism of gl ucose revealed two distinct groups of extract preparations, with no in termediate values. The values were -107.5 +/- 28.7 kJ mol(-1) and -30. 8 +/- 5.7 kJ mol(-1), respectively, while -100.0 kJ mol(-1) was predic ted from theoretical calculations. Kreuzberg and Betz(6) predicted rat e limiting effects of GAPDH in oscillating extracts. However, when pos sible effects of GAPDH on frequency, number of oscillations or total h eat production were examined, no influence of increasing or reducing t he initial GAPDH concentration could be found. The results are discuss ed with reference to existing models of glycolytic oscillations.