Table 2.

Calculated protein-ligand binding free energies and their components^a,^b

Ligand	TΔSc	ΔH (PB)d	ΔH (QM)e	ΔG (PB)f	ΔG (SIE)g	ΔG (QM)h	ΔG (Exp)
T1	−9.0 (0.2)	−40.7 (0.2)	−15.9 (0.2)	−31.7 (0.3)	−7.8 (0.01)	−6.9 (0.3)	−7.5 (0.2)
T2	−9.5 (0.4)	−38.0 (0.3)	−12.6 (0.2)	−28.4 (0.5)	−7.3 (0.02)	−3.1 (0.5)	−6.7 (0.3)
T3	−10.1 (0.2)	−37.2 (0.2)	−13.7 (0.2)	−27.0 (0.3)	−7.4 (0.01)	−3.6 (0.3)	−5.9 (0.2)
T4	no binding
T5	−8.8 (0.4)	−36.4 (0.2)	−16.5 (0.2)	−27.6 (0.4)	−7.5 (0.01)	−7.7 (0.5)	−7.8 (0.1)
P7	−12.9 (0.2)	−47.8 (0.2)	−17.3 (0.3)	−34.9 (0.2)	−8.7 (0.01)	−4.4 (0.3)	−7.8 (0.1)
PIi	n/a	n/a	n/a	0.71	0.78	0.78	n/a

^aValues of energies in kcal/mol

^bThe values in brackets represent the error of the mean.

^cEntropic contribution calculated according to eq 4.

^dEnthalpic part from MM/PB-SA calculation including internal and solvation free energy.

^eEnthalpic part from MM-QMSA calculation including internal energy and solvation free energy.

^fBinding free energy from MM/PB-SA calculation (eq 1)

^gBinding free energy from SIE calculation (eq 8)

^hBinding free energy from MM-QMSA calculation (eq 9).

ⁱPearlman’s predictive index.