Question

The direct phosphorylation of glucose by inorganic phosphate is a thermodynamically unfavorable reaction: glucose+Pi→glucoseglucose+Pi→glucose-66-phosphate+H2Ophosphate+H2O ΔG∘′=+3.3kcal/molΔG∘′=+3.3kcal/mol In...

The direct phosphorylation of glucose by inorganic phosphate is a thermodynamically unfavorable reaction:

glucose+Pi→glucoseglucose+Pi→glucose-66-phosphate+H2Ophosphate+H2O
ΔG∘′=+3.3kcal/molΔG∘′=+3.3kcal/mol

In the cell, glucose phosphorylation is accomplished by coupling the reaction to the hydrolysis of ATPATP, a highly exergonic reaction:

ATP+H2O→ADP+PiATP+H2O→ADP+Pi
ΔG∘′=−7.3kcal/molΔG∘′=−7.3kcal/mol

Typical concentrations of these intermediates in yeast cells are as follows:
[glucose-6-phospate] = 0.08mMmM
[ATP]=1.8mM[ATP]=1.8mM
[Pi]=1.0mM[Pi]=1.0mM
[ADP]=0.15mM[ADP]=0.15mM
Assume a temperature of 25∘C∘C for all calculations.

What minimum concentration of glucose would have to be maintained in a yeast cell for the coupled reaction to be thermodynamically spontaneous?

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Answer #1

Minimum concentration of Glucose is 7.712 nM

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