Excluded volume and ion-ion correlation effects on the ionic atmosphere around B-DNA: theory, simulations, and experiments.
Excluded volume and ion-ion correlation effects on the ionic atmosphere around B-DNA: theory, simulations, and experiments.
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DOI：
10.1063/1.4902407
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发表时间：
2014-12
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影响因子：
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通讯作者：
Zaven Ovanesyan;Bharat K. Medasani;M. O. Fenley;G. I. Guerrero-García;M. O. de la Cruz;M. Marucho
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文献类型：
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作者：
Zaven Ovanesyan;Bharat K. Medasani;M. O. Fenley;G. I. Guerrero-García;M. O. de la Cruz;M. Marucho
核酸周围的离子气氛调节其在盐水溶液中的稳定性。涉及核酸的生物学活动的复杂性的一个主要来源来自于周围离子和水分子对其结构和热力学性质的强烈影响。在这里，我们实现了一个经典的密度泛函理论的圆柱形聚电解质嵌入在含有明确的（中性硬球）水分子在实验溶剂浓度的水性电解质。我们的方法使我们能够包括离子相关性以及溶剂和离子排除体积效应研究高电荷的圆柱形聚电解质的结构和热力学性质。研究了生理浓度下水溶液电解质的大小和电荷不对称混合物的几种模型。我们的结果与Monte Carlo模拟吻合得很好。我们的数值计算显示显着的差异，在不同的含水电解质模型研究的离子密度分布。然而，我们的理论方法预测不同的含水电解质模型的B-DNA分子吸附的离子的过量数量的类似的结果。这些研究结果表明，离子计数实验数据不应单独用于验证水性DNA电解质模型的性能。
The ionic atmosphere around a nucleic acid regulates its stability in aqueous salt solutions. One major source of complexity in biological activities involving nucleic acids arises from the strong influence of the surrounding ions and water molecules on their structural and thermodynamic properties. Here, we implement a classical density functional theory for cylindrical polyelectrolytes embedded in aqueous electrolytes containing explicit (neutral hard sphere) water molecules at experimental solvent concentrations. Our approach allows us to include ion correlations as well as solvent and ion excluded volume effects for studying the structural and thermodynamic properties of highly charged cylindrical polyelectrolytes. Several models of size and charge asymmetric mixtures of aqueous electrolytes at physiological concentrations are studied. Our results are in good agreement with Monte Carlo simulations. Our numerical calculations display significant differences in the ion density profiles for the different aqueous electrolyte models studied. However, similar results regarding the excess number of ions adsorbed to the B-DNA molecule are predicted by our theoretical approach for different aqueous electrolyte models. These findings suggest that ion counting experimental data should not be used alone to validate the performance of aqueous DNA-electrolyte models.