Solvation effect on conformations of 1,2:dimethoxyethane: Charge-dependent nonlinear response in implicit solvent models

Jha, Abhishek; Freed, Karl F.

doi:10.1063/1.2815764

Cited by 47 publications

(35 citation statements)

References 60 publications

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“…1). Alternative analytical representations of this sigmoidal function have been used in molecular simulations by Ramstein and Lavery (23), Shen and Freed (22,24), and by Hassan et al (25) to study RNA, proteins, and ion solvation, respectively, generating results agreeing well with those from simulations with explicit solvent and/or experiment.…”

Section: Theorysupporting

confidence: 65%

“…1 A) due to the large disparity in their bulk static dielectric constants. When the ion is partially charged as is typical in biological systems such as proteins, the dependence of the relative permittivity on radial distance also shifts according to the scaling, z (r) ϭ unit-charge (r/ ͌ Z), where Z is the partial charge (22). Thus, as expected, smaller charges produce more rapid transitions to the bulk static limit, corresponding to weaker nonlinear effects in the vicinity of the ion.…”

Section: Resultsmentioning

confidence: 76%

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Influence of nonlinear electrostatics on transfer energies between liquid phases: Charge burial is far less expensive than Born model

Gong

Hocky

Freed

2008

Proc. Natl. Acad. Sci. U.S.A.

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The widely used Born model describes the electrostatic response of continuous media using static dielectric constants. However, when applied to a liquid environment, a comparison of Born model predictions with experimental values (e.g., transfer free energies and pK a shifts) found that agreement is only achieved by using physically unrealistic dielectric constants for proteins, lipids, etc., and/or equally unrealistic atomic radii. This leads to questions concerning the physical origins for this failure of the Born model. We partially resolve this question by applying the Langevin-Debye (LD) model of a continuous distribution of point, polarizable dipoles, a model that contains an added dependence of the electrostatic response on the solvent's optical dielectric constant and both gas-and liquid-phase dipole moments, features absent in the Born model to which the LD model reduces for weak fields. The LD model is applied to simple representations of three biologically relevant systems: (i) globular proteins, (ii) lipid bilayers, and (iii) membrane proteins. The linear Born treatment greatly overestimates both the self-energy and the transfer free energy from water to hydrophobic environments (e.g., a protein interior). By using the experimental dielectric constant, the energy cost of charge burial in either globular or membrane proteins of the Born model is reduced by almost 50% with the nonlinear theory as is the pKa shift, and the shifts agree well with experimental trends.Langevin-Debye model ͉ pKa shifts ͉ orientational polarization ͉ dielectric saturation and screening T he interaction of molecules and ions with various solvents is of importance in many physical, chemical, and biological systems. For example, electrostatics strongly influence enzyme catalysis, electron transfer, proton transport, ion channels, photo-activation, and ligand binding (1). Macroscopic dielectric continuum models are frequently invoked to describe solvation, especially in large biological systems where computations (using molecular mechanics, molecular dynamics, quantum mechanics, or combinations thereof) with explicit solvent molecules become prohibitive for many systems of physical interest. Although continuum models neglect certain microscopic details, the hope is to reduce the errors sufficiently by correctly describing the physics (2). Unfortunately, serious limitations have long been evident with one of the most popular models, the Born model (and the equivalent use of the Poisson equation), in which the solvent is characterized solely by the static dielectric constant. For example, Sandberg and Edholm concluded that the Born model introduces errors as large as 1,000 KJ/mol when used to predict the hydration energies of multivalent ions (3). The Born model is also frequently applied in evaluating the transfer free energy of ionizable groups between water and hydrophobic media, such as proteins and lipids, thereby predicting the pK a shift of a buried ionizable group. Multiple experiments and theoretical predictions agree tha...

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Section: Theorysupporting

confidence: 65%

Section: Resultsmentioning

confidence: 76%

Influence of nonlinear electrostatics on transfer energies between liquid phases: Charge burial is far less expensive than Born model

Gong

Hocky

Freed

2008

Proc. Natl. Acad. Sci. U.S.A.

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“…A more molecularly based approach accounting for the polarizability and permanent dipoles of the solvating molecules would be required to yield a more accurate expression for the solvation energy. 36,37 In this work, the electrolyte solution is investigated at the mean-field level, where the solvation energy retains the form of Born energy. However, the solvation energy is closely related to the fluctuation in a charged system, which includes both the local Born solvation effect and other long-range effects.…”

Section: Discussionmentioning

confidence: 99%

Effects of ion solvation on phase equilibrium and interfacial tension of liquid mixtures

Wang

2011

The Journal of Chemical Physics

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We study the bulk thermodynamics and interfacial properties of electrolyte solution mixtures by accounting for electrostatic interaction, ion solvation, and inhomogeneity in the dielectric medium in the mean-field framework. Difference in the solvation energy between the cations and anions is shown to give rise to local charge separation near the interface, and a finite Galvani potential between two coexisting solutions. The ion solvation affects the phase equilibrium of the solvent mixture, depending on the dielectric constants of the solvents, reflecting the competition between the solvation energy and translation entropy of the ions. Miscibility is decreased if both solvents have low dielectric constants and is enhanced if both solvents have high dielectric constant. At the mean-field level, the ion distribution near the interface is determined by two competing effects: accumulation in the electrostatic double layer and depletion in a diffuse interface. The interfacial tension shows a nonmonotonic dependence on the salt concentration: it increases linearly with the salt concentration at higher concentrations and decreases approximately as the square root of the salt concentration for dilute solutions, reaching a minimum near 1 mM. We also find that, for a fixed cation type, the interfacial tension decreases as the size of anion increases. These results offer qualitative explanations within one unified framework for the long-known concentration and ion size effects on the interfacial tension of electrolyte solutions.

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“…The solvation free energy is described in terms of various contributions such as the free energy of cavitation, electrostatic energy, dispersion energy, repulsion energy, and thermal fluctuations. In addition to the energetic parameters, the geometric measures are employed, such as the solute size, solventaccessible surface area, surface curvature and so on, to calculate the solvation free energy [55][56][57][58]. The implicit solvent approaches are computationally efficient and convenient for practical applications including drug screening [31,59,60].…”

Section: Introductionmentioning

confidence: 99%

Toward high-throughput predictions of the hydration free energies of small organic molecules from first principles

Jia

2016

Fluid Phase Equilibria

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Solvation effect on conformations of 1,2:dimethoxyethane: Charge-dependent nonlinear response in implicit solvent models

Cited by 47 publications

References 60 publications

Influence of nonlinear electrostatics on transfer energies between liquid phases: Charge burial is far less expensive than Born model

Influence of nonlinear electrostatics on transfer energies between liquid phases: Charge burial is far less expensive than Born model

Effects of ion solvation on phase equilibrium and interfacial tension of liquid mixtures

Toward high-throughput predictions of the hydration free energies of small organic molecules from first principles

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