Chapter 5, Problem 5.6PS

QUANTITATIVE The Equilibrium Constant. The following reaction is one of the steps in the glycolytic pathway, which we will encounter again in Chapter 9. You should recognize it already, however, because we used it as an example earlier (see Reaction 5-9):

$\text{glucose-6-phosphate}\rightleftharpoons \text{fructose-6-phosphate}$    (5-28)

The equilibrium constant K_eq for this reaction at 25°C is 0.5.

(a) Assume that you incubate a solution containing 0.15 M glucose-6-phosphate (G6P) overnight at 25°C with the enzyme phosphoglucoisomerase that catalyzes Reaction 5-28. How many millimoles of fructose-6-phosphate (F6P) will you recover from 10 mL of the incubation mixture the next morning?

(b) What answer would you get for part a if you had started with a solution containing 0.15 M F6P instead?

(c) What answer would you expect for part a if you had started with a solution containing 0.15 M G6P but forgot to add phosphoglucoisomerase to the incubation mixture?

(d) Would you be able to answer the question in part a if you had incubated at 15°C instead of 25°C? Why or why not?