Details zur Publikation
|DOI / URL||Link|
|Titel (primär)||A thermodynamic investigation of the glucose-6-phosphate isomerization|
|Autor||Hoffmann, P.; Held, C.; Maskow, T.; Sadowski, G.;|
|Journal / Serie||Biophysical Chemistry|
|POF III (gesamt)||T41;|
|Keywords||Thermodynamic equilibrium constant; Activity coefficient; Gibbs energy of reaction; Enthalpy of reaction; ePC-SAFT; Glycolysis|
In this work, ΔRg+ values for the enzymatic G6P isomerization were determined as a function of the G6P equilibrium molality between 25 °C and 37 °C. The reaction mixtures were buffered at pH = 8.5. In contrast to standard literature work, ΔRg+ values were determined from activity-based equilibrium constants instead of molality-based apparent values. This yielded a ΔRg+ value of 2.55 ± 0.05 kJ mol− 1 at 37 °C, independent of the solution pH between 7.5 and 8.5. Furthermore, ΔRh+ was measured at pH = 8.5 and 25 °C yielding 12.05 ± 0.2 kJ mol− 1.
Accounting for activity coefficients turned out to influence ΔRg+ up to 30% upon increasing the G6P molality. This result was confirmed by predictions using the thermodynamic model ePC-SAFT.
Finally, the influence of the buffer and of potassium glutamate as an additive on the reaction equilibrium was measured and predicted with ePC-SAFT in good agreement.
|Hoffmann, P., Held, C., Maskow, T., Sadowski, G. (2014):
A thermodynamic investigation of the glucose-6-phosphate isomerization
Biophys. Chem. 195 , 22 - 31