Multisite ion model in concentrated solutions of divalent cations (MgCl2 and CaCl2): osmotic pressure calculations.
Multisite ion model in concentrated solutions of divalent cations (MgCl2 and CaCl2): osmotic pressure calculations.
复制标题
DOI：
10.1021/jp507008x
复制
发表时间：
2015-01-08
期刊：
影响因子：
--
通讯作者：
García AE
中科院分区：
文献类型：
--
作者：
Saxena A;García AE
离子的准确力场参数对于蛋白质和核酸的有意义的模拟研究是必不可少的。目前接受的离子模型，特别是二价离子，不一定能再现Ca2+和Mg2+离子的正确生理行为。Saxena和Sept （J. chemistry）。定理。computer .2013, 9, 3538-3542)描述了一种称为多位点离子模型的模型，该模型不是将离子视为孤立的球体，而是将电荷分成具有部分电荷的多个位点。该模型提供了离子与生物分子的准确内壳配位，并预测了蛋白质和核酸的更好的自由能。在这里，我们扩展和完善了多位点模型来描述二价离子在浓MgCl2和CaCl2电解质溶液中的行为，消除了原始模型中出现的不寻常的离子-离子配对和离子聚集。我们通过将MgCl2浓溶液的渗透压与实验值相匹配来校准和改进多点模型的参数，然后使用这些参数来测试CaCl2溶液的行为。我们发现两种二价离子的浓溶液在正确的渗透压下表现出实验观察到的行为，存在溶剂分离的离子对而不是直接的离子对，并且没有离子聚集。改进的（Mg2+和Ca2+）多位点模型可用于生理相关盐浓度下生物分子的经典模拟。
Accurate force field parameters for ions are essential for meaningful simulation studies of proteins and nucleic acids. Currently accepted models of ions, especially for divalent ions, do not necessarily reproduce the right physiological behavior of Ca2+ and Mg2+ ions. Saxena and Sept (J. Chem. Theor. Comput.2013, 9, 3538–3542) described a model, called the multisite-ion model, where instead of treating the ions as an isolated sphere, the charge was split into multiple sites with partial charge. This model provided accurate inner shell coordination of the ion with biomolecules and predicted better free energies for proteins and nucleic acids. Here, we expand and refine the multisite model to describe the behavior of divalent ions in concentrated MgCl2 and CaCl2 electrolyte solutions, eliminating the unusual ion–ion pairing and clustering of ions which occurred in the original model. We calibrate and improve the parameters of the multisite model by matching the osmotic pressure of concentrated solutions of MgCl2 to the experimental values and then use these parameters to test the behavior of CaCl2 solutions. We find that the concentrated solutions of both divalent ions exhibit the experimentally observed behavior with correct osmotic pressure, the presence of solvent separated ion pairs instead of direct ion pairs, and no aggregation of ions. The improved multisite model for (Mg2+ and Ca2+) can be used in classical simulations of biomolecules at physiologically relevant salt concentrations.
登录
查看更多内容
影响因子：
5.5
作者：
Hess, Berk;Kutzner, Carsten;Lindahl, Erik
通讯作者：
Lindahl, Erik
影响因子：
3.3
作者：
Chen, Alan A.;Pappu, Rohit V.
通讯作者：
Pappu, Rohit V.
影响因子：
2.9
作者：
Callahan, Karen M.;Casillas-Ituarte, Nadia N.;Tobias, Douglas J.
通讯作者：
Tobias, Douglas J.
影响因子：
3.3
作者：
Gavryushov, Sergei
通讯作者：
Gavryushov, Sergei
影响因子：
5.5
作者：
Allner, Olof;Nilsson, Lennart;Villa, Alessandra
通讯作者：
Villa, Alessandra