Abstract
The occupancy distribution of water molecules in the first hydration shell around a solute is intimately connected with solvent density fluctuations and is of fundamental interest in understanding hydration. The free energies to evacuate the first hydration shell around a solute and a cavity defined by the first hydration shell depend on the system size, emphasizing that the solvent density fluctuations are themselves dependent on the system size. This observation interpreted within the quasichemical theory shows that both the hydrophilic and the hydrophobic contributions to hydration depend on the system size, decreasing with increasing system size. The net hydration free energy benefits somewhat from the compensation of hydrophilic and hydrophobic contributions; nevertheless a large system appears necessary to describe correctly the balance of these contributions in the hydration of the macromolecule.
| Original language | English |
|---|---|
| Pages (from-to) | 798-806 |
| Number of pages | 9 |
| Journal | Journal of Physical Chemistry B |
| Volume | 124 |
| Issue number | 5 |
| DOIs | |
| State | Published - Feb 6 2020 |
| Externally published | Yes |
Funding
We gratefully acknowledge computing support from National Energy Research Scientific Computing Center, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. We thank Purushottam Dixit, Walter Chapman, and Lawrence Pratt for helpful comments. We thank Vyatautas Gapsys and Bert de Groot for helpful discussions and for sharing molecular structures. We thank the anonymous reviewers for their thought provoking comments.