Department of Food Science, Rutgers University, 65 Dudley Road, New Brunswick, New Jersey 08901, USA.
J Phys Chem B. 2012 Mar 15;116(10):3045-53. doi: 10.1021/jp206527p. Epub 2012 Feb 8.
In protein-polysaccharide complex systems, how nonspecific interactions such as electrostatic and van der Waals interactions affect complex formation has not been clearly understood. On the basis of a coarse-grained model with the specificity of a target system, we have applied Monte Carlo (MC) simulation to illustrate the process of complex coacervate formation from the association of proteins and polysaccharides. The coarse-grained model is based on serum albumin and a polycation system, and the MC simulation of pH impact on complex coacervation has been carried out. We found that complex coacervates could form three ways, but the conventional association through electrostatic attraction between the protein and polysaccharide still dominated the complex coacervation in such systems. We also observed that the depletion potential always participated in protein crowding and was weakened in the presence of strong electrostatic interactions. Furthermore, we observed that the sizes of polysaccharide chains nonmonotonically increased with the number of bound proteins. Our approach provides a new way to understand the details during protein-polysaccharide complex coacervation at multiple length scales, from interaction and conformation to aggregation.
在蛋白质-多糖复合体系中，静电作用和范德华力等非特异性相互作用如何影响复合物的形成还没有得到清晰的认识。基于具有目标体系特异性的粗粒化模型，我们应用蒙特卡罗（MC）模拟阐明了蛋白质和多糖之间的缔合形成凝聚相的过程。该粗粒化模型基于血清白蛋白和聚阳离子体系，进行了 pH 值对凝聚相形成影响的 MC 模拟。我们发现凝聚相可以通过三种方式形成，但在这样的体系中，蛋白质和多糖之间通过静电吸引力的常规缔合仍然占据主导地位。我们还观察到，消耗势总是参与蛋白质拥挤，并在存在强静电相互作用时减弱。此外，我们观察到多糖链的尺寸随结合蛋白数量的增加呈非单调变化。我们的方法为从相互作用、构象到聚集等多个长度尺度理解蛋白质-多糖复合凝聚相提供了一种新的途径。
