Specific ion effects in solutions of globular proteins:: Comparison between analytical models and simulation

被引:53
作者
Boström, M
Tavares, FW
Bratko, D
Ninham, BW
机构
[1] Linkoping Univ, Dept Phys & Measurement Technol, SE-58183 Linkoping, Sweden
[2] Univ Fed Rio de Janeiro, Escola Quim, Rio De Janeiro, Brazil
[3] Virginia Commonwealth Univ, Dept Chem, Richmond, VA 23284 USA
[4] Australian Natl Univ, Res Sch Phys Sci & Engn, Canberra, ACT 0200, Australia
关键词
D O I
10.1021/jp0551869
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
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.
引用
收藏
页码:24489 / 24494
页数:6
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