Table 3. Comparison of Calculated and Observed Solvation Free Energies (ΔGhyd, kcal/mol), and Ion–Water Oxygen Distances (M2+–O, Å) Employing Parameters Developed by Åqvist and Warshel17,32 for Mn2+ and Zn2+ Dummy Models, by Oelschlaeger et al.31 for Mg2+ Dummy Model, and by Saxena and Sept39 for Ca2+ Dummy Model. For Comparison, the Results Using Soft-sphere Models are also Presented in Table S1.a.
TIP3P |
experimental |
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e | AiM | BiM | mM | AiD | BiD | mD | ΔGhyd | M2+–Oa | ΔGhyd54 | M2+–O52 | |
Mnb | –0.1 | 145 | 25.0 | 48.94 | 0.00 | 0.00 | 1.0 | –440.9 ± 0.1 | 2.14 ± 0.05 | –436.4 | 2.20 |
Znb | –1.0 | 136 | 41.0 | 59.38 | 0.00 | 0.00 | 1.0 | –479.5 ± 0.1 | 2.07 ± 0.04 | –483.3 | 2.08 |
Mgc | –1.0 | 70.0 | 41.0 | 6.3 | 0.05 | 0.00 | 3.0 | –484.9 ± 0.1 | 2.08 ± 0.03 | –454.2 | 2.10 |
Cad | 0.0 | 233.2 | 35.5 | 33.1 | 0.05 | 0.00 | 1.0 | –408.6 ± 0.2 | 2.32 ± 0.02 | –379.5 | 2.39–2.4676,77 |
All values are averages and standard deviations over five trajectories, as outlined in the main text. M–O distances for all of the water molecules bound to the metal were monitored along the simulation. Only for calcium, which shows a rapid water exchange, the M–O distance was directly taken from the peak of the RDF (see Supporting Information Figure S1).
Kb = 1600 (kcal mol−1Å−2) and Kθ = 250 (kcal mol−1rad−2) and no bond between dummies.
Kb = 640 (kcal mol−1Å−2) and Kθ = 55 (kcal mol−1rad−2).
Kb = 540 (mol−1Å−2) and Kθ =55 (kcal mol−1rad−2) and no bond between dummies.