Table 2.

Inhibition constants for HIV-1 proteases from different subtypes

Inhibitor	Ki (nM), subtype B	Ki (nM), subtype A	Ki (nM), subtype C
Indinavir	0.8  ± 0.06	5.1  ± 0.2	2.5  ± 0.2
Ritonavir	0.05  ± 0.005	0.36  ± 0.03	0.23  ± 0.02
Saquinavir	0.5  ± 0.03	1.2  ± 0.08	1.1  ± 0.05
Nelfinavir	1.0  ± 0.07	2.6  ± 0.2	2.1  ± 0.1

Inhibition constants, K_i, for the inhibitors indinavir, ritonavir, saquinavir, and nelfinavir were obtained at 25°C by measuring the rate of substrate hydrolysis using 15–30 nM Protease in 10 mM sodium acetate, 1 M NaCl, pH 5.0, and 42.5 μM substrate plus increasing amounts of inhibitor.