Question

The glucose/glucose-6-phosphate substrate cycle involves distinct reactions of glycolysis and gluconeogenesis that interconvert these two metabolites. Assume that under physiological conditions, [ATP]=[ADP] and [Pi]=1mM.
Consider the following glycolytic reaction catalyzed by hexokinase:

ATP+glucose⇌ADP+glucose−6−phosphateΔG∘′=−16.7kJ/mol

Calculate the equilibrium constant (K) for this reaction at 298 K,

From the equilibrium constant, calculate the maximum [glucose-6-phosphate]/[glucose] ratio that would exist under conditions where the reaction is still thermodynamically favorable.

The reverse of this interconversion in gluconeogenesis is catalyzed by glucose-6-phosphatase:

glucose−6−phosphate+H2O⇌glucose+PiΔG∘′=−13.8kJ/mol

K= 262 for this reaction. Calculate the maximum ratio of [glucose]/[glucose-6-phosphate] that would exist under conditions where the reaction is still thermodynamically favorable.

Answer 1