Chemical and Materials Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
J Phys Chem B. 2012 Jun 28;116(25):7492-8. doi: 10.1021/jp301859z. Epub 2012 Jun 15.
Specific ion interactions between alkali cations (i.e., Li(+), Na(+), and K(+)) and an acetate anion in aqueous solution were studied using molecular dynamics simulation techniques and polarizable potential models. The ions-acetate systems were used as a model for understanding the interactions between ions and protein surfaces. We computed free energy profiles for different ion pairs using constrained mean force methods. Upon analyzing the computed free energy profiles for the Na(+)/K(+)-acetate ion-pairs, we observed a deeper contact ion minimum and also a larger association constant for the Na(+)-acetate pair as compared to the corresponding K(+)-acetate pair. These observations help to demonstrate the preferential binding of Na(+) over K(+) to protein surfaces. We also applied various rate theories to study the kinetics of ion pair interconversion.
使用分子动力学模拟技术和极化势能模型研究了碱金属阳离子（即 Li(+)、Na(+) 和 K(+)）与水溶液中醋酸根阴离子之间的特定离子相互作用。离子-醋酸根体系被用作理解离子与蛋白质表面相互作用的模型。我们使用约束平均力方法计算了不同离子对的自由能曲线。通过分析 Na(+)/K(+)-醋酸根离子对的计算自由能曲线，我们观察到 Na(+)-醋酸根对的接触离子最小能更深，并且其缔合常数也大于相应的 K(+)-醋酸根对。这些观察结果有助于证明 Na(+)优先与蛋白质表面结合。我们还应用各种速率理论研究了离子对相互转换的动力学。
