Protein A can bind to each of the proteins B or C. The association rate constants are the same for forming the AB and the AC complexes. However, the dissociation rate constant for AB is 100 times higher than that for AC. Given that every tenfold increase in the equilibrium constant (of the association reaction) corresponds to about -5.9 kJ/mole difference in the standard free-energy change for the reaction (ΔG°), what is the value of (ΔG°AB - ΔG°AC) in kJ/mole?
A) -11.8
B) -5.9
C) 0
D) +5.9
E) +11.8

Question

Quizplus · Accepted Answer

The equilibrium constant for complex formation is equal to the ratio of association and dissociation rate constants; thus, it is 100 times higher for AC compared to AB. This makes ΔG°AB more positive than ΔG°AC by a 11.8 kJ/mole difference.

Protein a Can Bind to Each of the Proteins B