Biochemistry 4th Edition by Reginald Garrett, Charles Grisham

Exercise 15

Energetics of 1,3-bisphophoglycerate hydrolysis
(Integrates with Chapter 3.) The standard free energy change ( G°') for hydrolysis of 1,3- bisphosphoglycerate (1,3-BPG) tO₃-phosphoglycerate (3-PG) and Pi is -49.6 kJ/mol:
1,3-BPG + H2O 3-PG + Pi
The standard free energy change ( G°') for ATP hydrolysis is -30.5 kJ/mol:
ATP + H2O ADP + Pi
a. What is the standard free energy change for the phosphoglycerate kinase reaction:
ADP + 1,3-BPG ATP + 3-PG
b. What is the equilibrium constant for this reaction
c. If the steady-state concentrations of [1,3-BPG] and [3-PG] in an erythrocyte are 1 µM and 129 µM, respectively, what will be the ratio of [ATP]/[ADP], assuming the phosphoglycerate kinase reaction is at equilibrium