An antibody binds to another protein with an equilibrium constant, K, of 5 × 10⁹ M^–1. When it binds to a second, related protein, it forms three fewer hydrogen bonds, reducing its binding affinity by 11.9 kJ/mole. What is the K for its binding to the second protein? (Free-energy change is related to the equilibrium constant by the equation ΔG° = –2.3 RT log K, where R is 8.3 × 10^–3 kJ/(mole K) and T is 310 K.)