Table 2.

Average contribution of background charges, $G_{\text{BB}}(\overline{x})$, to the calculated total free energy (kcal·mol⁻¹).

protein	Aexact GBB	BGBBsol
1a2p	−467.3 (0.3)	−467.3
1pga	−29.6 (0.2)	−29.5
1ppf	−156.8 (0.1)	−156.7
2lzt	−1092.6 (0.3)	−1092.5
2trx	−117.8 (0.2)	−117.8
3bdc	−443.3 (0.3)	−443.3
3rn3	−524.1 (0.9)	−524.2
4pti	−465.1 (0.1)	−465.2

^AThe average value of the exact $G_{\text{BB}}(\overline{x})$ computed for the most populated protonation states for each titratable residue in the proteins; standard deviations are given in parenthesis

^B$G_{\text{BB}}(\overline{x})$ obtained as a solution to the system of equations 9.