Contributions of Far-Field Hydrodynamic Interactions to the Kinetics of Electrostatically Driven Molecular Association
Contributions of Far-Field Hydrodynamic Interactions to the Kinetics of Electrostatically Driven Molecular Association
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DOI：
10.1021/jp301265y
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发表时间：
2012-05-10
影响因子：
3.3
通讯作者：
Trylska, Joanna
中科院分区：
文献类型：
--
作者：
Dlugosz, Maciej;Antosiewicz, Jan M.;Trylska, Joanna
我们用布朗动力学模拟了模型各向同性和各向异性分子在周期系统中的扩散相遇。我们考虑了扩散分子之间的静电力、排斥体积力和远场流体动力。我们的目标是估计在何种程度上的流体动力学相互作用影响的关联动力学时，关联的合作伙伴是带相反的电荷和他们的直接静电相互作用的小移动的离子的溶解盐筛选。总体而言，包括流体动力学相互作用降低了缔合速率常数。这种减少的相对幅度不依赖于各向同性带电物体的关联的离子强度。这也适用于非特异性关联（即，不限制结合配偶体在接触复合体中的相对取向）。然而，这种依赖性是可见的各向异性对象的特定于方向的关联。此外，我们观察到，各向异性分子的一些取向是流体动力学有利的，在他们的相互方法，这样的分子可以流体动力学转向一个特定的相对取向。在强静电相互作用或空间位阻的情况下，这种流体动力学取向转向受到阻碍。
We simulated the diffusional encounters in periodic systems of model isotropic and anisotropic molecules using Brownian dynamics. We considered the electrostatic, excluded volume, and far-field hydrodynamic forces between diffusing molecules. Our goal was to estimate to what extent the hydrodynamic interactions influence the association kinetics when the associating partners are oppositely charged and their direct electrostatic interactions are screened by small mobile ions of dissolved salt. Overall, including hydrodynamic interactions decreases the association rate constants. The relative magnitude of this decrease does not depend on the ionic strength for the association of isotropic charged objects. This also holds true for nonspecific association (i.e., without restrictions regarding the relative orientation of binding partners in an encounter complex) of anisotropic objects. However, such dependence is visible for orientation-specific association of anisotropic objects. Moreover, we observe that some orientations of anisotropic molecules are hydrodynamically favorable during their mutual approach, and that such molecules can be hydrodynamically steered toward a particular relative orientation. This hydrodynamic orientational steering is impeded in case of strong electrostatic interactions or steric hindrance.