Table 2.

Thermodynamic parameters for APV, DRV, and ATV binding to WT, I50V/A71V, and I50L/A71V HIV-1 proteases

Inhibitor and protease variant	Kd (nM)	Kd ratioa	ΔH (kcal mol−1)	−TΔS (kcal mol−1)	ΔG (kcal mol−1)
APV
WT	0.39 ± 0.20	1.0	−7.3 ± 0.9	−5.3	−12.6
I50V/A71V	0.88 ± 0.02	2.2	−11.8 ± 0.3	−0.3	−12.1
I50L/A71V	0.14 ± 0.02	0.4	−9.5 ± 0.2	−3.8	−13.2
DRV
WT	0.004 ± 0.002	1.0	−12.1 ± 0.8	−3.1	−15.2
I50V/A71V	0.067 ± 0.021	16.7	−12.0 ± 0.6	−1.6	−13.6
I50L/A71V	0.016 ± 0.001	4.0	−13.4 ± 0.9	−1.1	−14.5
ATV
WT	0.23 ± 0.12	1.0	−1.1 ± 0.2	−11.8	−12.9
I50V/A71V	0.03 ± 0.01	0.1	−7.3 ± 1.1	−6.6	−13.9
I50L/A71V	0.65 ± 0.05	2.8	−3.6 ± 0.4	−8.7	−12.3

^aFold change with respect to WT protease.