Table 1. Binding free energy and fragment molecular orbital energy (kcal mol⁻¹) of HIV-1 PR with its inhibitor compared with experimental values: (a) a complex crystal with cyclic urea (XK2) and three (XK1, XK3, XK4) modelled from XK2 (1hvr); (b) two complex crystals with cyclic urea (AH1; 1ajx) and a dipeptide BEH (1d4h).

Inhibitor	(nM)
(a)
XK1	4.7	−11.43	−32.37	−39.34
XK2	0.31	−13.05	−57.03	−39.85
XK3	2.14	−11.94	−37.28	−36.96
XK4	0.27	−13.13	−46.56	−49.51
(b)
AH1	12.2	−10.86	−46.22	−70.01
BEH	0.10	−13.73	−54.38	−47.00