Consider the final reaction in the citric acid cycle, catalyzedby malate dehydrogenase:
Malate + NAD+  ⇄ oxaloacetate + NADH + H+
Equilibrium concentrations of the reaction components weremeasured as follows:
[malate] = 5.28 mM
[NAD+] = 75 uM
[oxaloacetate] = 14.5 uM
[NADH] = 14.5 uMï‚·
pH = 8.83
a) From these data calculate the equilibrium constant, Keq, forthis reaction.
b) Calculate the standard free-energy change, ΔG°’, for thisreaction (hint: remember that
the prime means that the standard [H+] is 1.0 × 10-7 M, not 1M)
c) Calculate the actual free-energy, ΔG, under the followingconditions:
ï‚· [malate] = 6.0 mM
[NAD+] = 100 uM
[oxaloacetate] = 0.001 uM
[NADH] = 0.0001 uM
pH = 8.83
