Departament de Fisica Fonamental, Facultat de Fisica, Universitat de Barcelona, Marti i Franques 1, 08028 Barcelona, Spain.
Eur Biophys J. 2013 Sep;42(9):661-72. doi: 10.1007/s00249-013-0915-z. Epub 2013 May 31.
The salt dependent radius of gyration of a polyelectrolyte in aqueous solution is calculated in an environment where the polyelectrolyte is surrounded by a permeable membrane that exchanges only solvent particles with the bulk. We obtain additionally the scaling exponent of the gyration radius as a function of the polymerization degree, and find that the polyelectrolyte retains a stretched conformation during the condensation and re-expansion process, indicating that these effects are of an electrostatic nature. The solvent quality is also shown to affect the polyelectrolyte conformation, especially for the poor solvent case. These results are obtained using a hybridized Monte Carlo technique with the coarse-grained, dissipative particle dynamics method with fluctuating number of solvent particles. The full range of the electrostatic interactions is included in the simulations, using the Ewald sum method, and the counterions and solvent molecules are included explicitly. In the complex systems mentioned above, the electrostatic interactions and the solvent quality play a key role in understanding phenomena that do not occur in uncharged systems. Our results are compared and validated with the behavior of some biomolecules under similar environments.
在一种环境中，计算了带电荷聚合物在水溶液中的盐依赖回旋半径，其中聚合物被可渗透的膜包围，该膜仅与本体交换溶剂颗粒。我们还获得了旋半径作为聚合度的函数的标度指数，并发现聚合物在凝聚和再膨胀过程中保持伸展构象，表明这些效应具有静电性质。溶剂质量也显示出对聚合物构象的影响，特别是对不良溶剂的情况。这些结果是使用混合蒙特卡罗技术与粗粒度耗散粒子动力学方法与溶剂粒子的波动数获得的。使用 Ewald 求和法在模拟中包含了全范围的静电相互作用，并显式包含了抗衡离子和溶剂分子。在上述复杂系统中，静电相互作用和溶剂质量在理解未带电系统中不会发生的现象方面起着关键作用。我们的结果与类似环境下一些生物分子的行为进行了比较和验证。
