title: A self-consistent phase-field approach to implicit solvation of charged molecules with Poisson-Boltzmann electrostatics.
abstract: Dielectric boundary based implicit-solvent models provide efficient descriptions of coarse-grained effects, particularly the electrostatic effect, of aqueous solvent. Recent years have seen the initial success of a new such model, variational implicit-solvent model (VISM) [Dzubiella, Swanson, and McCammon Phys. Rev. Lett. 96, 087802 (2006) and J. Chem. Phys. 124, 084905 (2006)], in capturing multiple dry and wet hydration states, describing the subtle electrostatic effect in hydrophobic interactions, and providing qualitatively good estimates of solvation free energies. Here, we develop a phase-field VISM to the solvation of charged molecules in aqueous solvent to include more flexibility. In this approach, a stable equilibrium molecular system is described by a phase field that takes one constant value in the solute region and a different constant value in the solvent region, and smoothly changes its value on a thin transition layer representing a smeared solute-solvent interface or dielectric boundary. Such a phase field minimizes an effective solvation free-energy functional that consists of the solute-solvent interfacial energy, solute-solvent van der Waals interaction energy, and electrostatic free energy described by the Poisson-Boltzmann theory. We apply our model and methods to the solvation of single ions, two parallel plates, and protein complexes BphC and p53/MDM2 to demonstrate the capability and efficiency of our approach at different levels. With a diffuse dielectric boundary, our new approach can describe the dielectric asymmetry in the solute-solvent interfacial region. Our theory is developed based on rigorous mathematical studies and is also connected to the Lum-Chandler-Weeks theory (1999). We discuss these connections and possible extensions of our theory and methods.
authors.affiliation: Department of Mathematics, University of California, San Diego, 9500 Gilman Drive, Mail Code 0112. La Jolla, California 92093-0112, USA.
authors.forename: Hui
authors.initials: H
authors.lastname: Sun
authors.affiliation: Department of Mathematics, University of California, San Diego, 9500 Gilman Drive, Mail Code 0112. La Jolla, California 92093-0112, USA.
authors.forename: Jiayi
authors.initials: J
authors.lastname: Wen
authors.affiliation: Department of Mathematics, the George Washington University, Monroe Hall, 2115 G St. NW, Washington, DC 20052, USA.
authors.forename: Yanxiang
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Department of Mathematics and Quantitative Biology Graduate Program, University of California, San Diego, 9500 Gilman Drive, Mail Code 0112. La Jolla, California 92093-0112, USA.
authors.forename: Bo
authors.initials: B
authors.lastname: Li
authors.affiliation: Department of Chemistry and Biochemistry, Department of Pharmacology, and Howard Hughes Medical Institute, University of California, San Diego, La Jolla, California 92093-0365, USA.
authors.forename: J Andrew
authors.initials: JA
authors.lastname: McCammon
mesh_terms: D057927:Hydrophobic and Hydrophilic Interactions; D056004:Molecular Dynamics Simulation; D016012:Poisson Distribution; D011506:Proteins / Q000737:chemistry*; D012995:Solubility; D012997:Solvents / Q000737:chemistry; D055672:Static Electricity; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D011506:Proteins; D012997:Solvents; D014867:Water