Becker's World of the Cell 9th Edition by Lewis Kleinsmith, Jeff Hardin, Gregory Paul Bertoni

Exercise 7

Calculating G°' and G'. Like Reaction 5-28, the conversion of 3-phosphoglycerate (3PG)to 2-phosphoglycerate (2PG)is an important cellular reaction because it is one of the steps in the glycolytic pathway:
(1)
If the enzyme that catalyzes this reaction is added to a solution of 3PG at 25°C and pH 7.0, the equilibrium ratio between the two species will be 0.165:
(2)
Experimental values for the actual steady-state concentrations of these compounds in human red blood cells are 61 M for 3PG and 4.3 M for 2PG.
(a)Calculate G°'. Explain in your own words what this value means.
(b)Calculate G'. Explain in your own words what this value means. Why are G' and G°' different
(c)If conditions in the cell change such that the concentration of 3PG remains fixed at 61 M but the concentration of 2PG begins to rise, how high can the 2PG concentration get before Reaction 5-29 will cease because it is no longer thermodynamically feasible