Specific Ion Effects in Solutions of Globular Proteins: Comparison between Analytical Models and Simulation

Date

2005

Authors

Bostrom, Mathias Anders
Tavares, Frederico W
Bratko, D.
Ninham, Barry

Journal Title

Journal ISSN

Volume Title

Publisher

American Chemical Society

Abstract

Monte Carlo simulations have been performed for ion distributions outside a single globular macroion and for a pair of macroions, in different salt solutions. The model that we use includes both electrostatic and van der Waals interactions between ions and between ions and macroions. Simulation results are compared with the predictions of the Ornstein-Zernike equation with the hypernetted chain closure approximation and the nonlinear Poisson-Boltzmann equation, both augmented by pertinent van der Waals terms. Ion distributions from analytical approximations are generally very close to the simulation results. This demonstrates that properties that are related to ion distributions in the double layer outside a single interface can to a good approximation be obtained from the Poisson-Boltzmann equation. We also present simulation and integral equation results for the mean force between two globular macroions (with properties corresponding to those of hen-egg-white lysozyme protein at pH 4.3) in different salt solutions. The mean force and potential of mean force between the macroions become more attractive upon increasing the polarizability of the counterions (anions), in qualitative agreement with experiments. We finally show that the deduced second virial coefficients agree quite well with experimental results.

Description

Keywords

Keywords: Nonlinear Poisson-Boltzmann equation; Ornstein-Zernike equation; Single globular macroion; Van der Waals interactions; Computer simulation; Electrostatics; Polarization; Proteins; Salts; Ions; hen egg lysozyme; ion; lysozyme; animal; article; chemistry; c

Citation

Source

Journal of Physical Chemistry B

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

DOI

10.1021/jp0551869

Restricted until

2037-12-31