Understanding Protein Diffusion in Polymer Solutions: A Hydration with Depletion Model
Understanding Protein Diffusion in Polymer Solutions: A Hydration with Depletion Model
复制标题
了解聚合物溶液中的蛋白质扩散：水合与消耗模型
DOI：
10.1021/acs.jpcb.6b06248
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发表时间：
2016-09-29
影响因子：
3.3
通讯作者：
Hou, Zhonghuai
中科院分区：
文献类型：
--
作者：
Feng, Xiaoqing;Chen, Anpu;Hou, Zhonghuai
了解蛋白质在聚合物溶液中的扩散对于模拟体内过程具有普遍的重要性。在这里，我们提出了一个理论框架来分析球形蛋白在半稀聚合物溶液中的平移和旋转扩散的解耦。蛋白质被建模为具有有效流体动力学半径的球形粒子，被耗尽层包围。根据聚合物溶液宏观黏度的标度公式和耗竭效应的平均场理论，确定了耗竭区黏度随空间变化的分布。根据经典流体力学的格式，可以对施加在蛋白质上的水动力阻力和扭矩进行数值计算，从而使我们能够获得平移和旋转扩散系数。我们已经应用我们的模型来研究蛋白质在两种特定的聚合物溶液系统中的扩散，即聚乙二醇（PEG）和葡聚糖。引人注目的是，我们的理论结果可以很好地定量再现实验结果，并充分再现了实验中观察到的平移扩散和旋转扩散之间的解耦。此外，我们的模型有助于深入了解蛋白质的有效流体动力半径如何随聚合物系统而变化。我们发现，蛋白质在PEG溶液中的有效水动力半径与在纯水中几乎相同，这表明PEG诱导了优先水化，而在葡聚糖溶液中，由于蛋白质和葡聚糖分子之间更强的吸引力相互作用，它通常会增强。
Understanding the diffusion of proteins in polymer solutions is of ubiquitous importance for modeling processes in vivo. Here, we present a theoretical framework to analyze the decoupling of translational and rotational diffusion of globular proteins in semidilute polymer solutions. The protein is modeled as a spherical particle with an effective hydrodynamic radius, enveloped by a depletion layer. On the basis of the scaling formula of macroscopic viscosity for polymer solutions as well as the mean-field theory for the depletion effect, we specify the space-dependent viscosity profile in the depletion zone. Following the scheme of classical fluid mechanics, the hydrodynamic drag force as well as torque exerted to the protein can be numerically evaluated, which then allows us to obtain the translational and rotational diffusion coefficients. We have applied our model to study the diffusion of proteins in two particular polymer solution systems, i.e., poly(ethylene glycol) (PEG) and dextran. Strikingly, our theoretical results can reproduce the experimental results quantitatively very well, and fully reproduce the decoupling between translational and rotational diffusion observed in the experiments. In addition, our model facilitates insights into how the effective hydrodynamic radius of the protein changes with polymer systems. We found that the effective hydrodynamic radius of proteins in PEG solutions is nearly the same as that in pure water, indicating PEG induces preferential hydration, while, in dextran solutions, it is generally enhanced due to the stronger attractive interaction between protein and dextran molecules.