Table 2. Calculated gas phase QM energies Eqm, free energies of solvation ΔGsolv, and differences in free energy change ΔΔG for ionizing the Asp’s in the 8 protonation configurations using capped Asp as the reference compound. All the ΔΔG values are relative to the minimum among the 8 configurations. All the values are in the unit of kcal/mol.
| Protocol I | Protocol II | Protocol III | |||||||
|---|---|---|---|---|---|---|---|---|---|
| State | Eqm | ΔGsolv | ΔΔG | Eqm | ΔGsolv | ΔΔG | Eqm | ΔGsolv | ΔΔG |
| 32i | -34763.3 | -3593.4 | 0.0 | -34783.2 | -3587.5 | 0.0 | -34786.7 | -3237.3 | 6.2 |
| 228i | -34757.0 | -3597.3 | 2.4 | -34766.8 | -3595.5 | 8.3 | -34787.3 | -3242.9 | 0.0 |
| 32o | -34761.0 | -3592.8 | 2.9 | -34768.9 | -3594.3 | 7.4 | -34780.7 | -3240.0 | 9.5 |
| 228o | -34753.5 | -3597.4 | 5.8 | -34768.4 | -3589.1 | 13.1 | -34783.0 | -3243.2 | 4.0 |
| 228i32o | -34825.6 | -3440.2 | 6.1 | -34845.8 | -3426.9 | 13.1 | -34836.9 | -3094.7 | 13.8 |
| 228o32i | -34821.2 | -3439.8 | 10.9 | -34830.1 | -3435.0 | 20.7 | -34839.6 | -3101.7 | 4.2 |
| t32 | -34640.3 | -3766.7 | 34.5 | -34658.1 | -3756.7 | 40.6 | -34679.8 | -3402.3 | 32.8 |
| t228 | -34637.3 | -3766.5 | 37.7 | -34657.2 | -3755.7 | 42.6 | -34676.1 | -3401.6 | 37.3 |