Figure 5.

Gibbs free energy changes (ΔΔG) upon binding with mutant cdMMP-14 over wt. Values of IC₅₀ (nanomolar) were measured by a competitive ELISA, and ΔΔG_(mut-wt) (kilocalories per mole) values were calculated by the equation $\Delta \Delta G=\mathit{RT}\text{ln}\frac{{\text{IC}}_{50}(\text{Ala}\text{mutant})}{{\text{IC}}_{50}(\text{wild}\text{type})}$, where R = 1.987 cal K⁻¹ mol⁻¹ and T = 298 K. A positive ΔΔG (>0.5 kcal/mol, red) indicates that the binding affinity is weakened with the mutant; a negative ΔΔG (less than −0.5 kcal/mol, blue) indicates that the binding affinity is enhanced with the mutant, and a |ΔΔG| of <0.5 kcal/mol (white) suggests a nonsignificant change.