Yan Zhiqiang, Wang Jun, Zhang Jian, Qin Meng, Wang Wei
National Laboratory of Solid State Microstructure and Department of Physics, Nanjing University, Nanjing 210093, China.
Phys Rev E Stat Nonlin Soft Matter Phys. 2010 Sep;82(3 Pt 1):031917. doi: 10.1103/PhysRevE.82.031917. Epub 2010 Sep 30.
The structures of the peptides and their assembly are largely modulated by the environment. To discover the physical principles governing the structural modulations of peptides by the environment would be useful for many applications. As the typical examples, the structures of three kinds of ionic-complementary EAK16-family peptides under various environmental conditions are studied with simulations in this work. A model with intermediate resolution is used, in which both the backbone hydrogen bonds and electrostatic interactions are explicitly considered. The thermodynamics of these peptides (including the free energy and heat capacity) are described for various strengths of the electrostatic interactions which reflect the variation of environment. With these results, the phase diagrams of these peptides related to the temperature and the strength of electrostatic interactions are presented and compared. Based on the differences in the phase structures of the peptide, the different aggregation behaviors are explained based on the monomeric structural features of the peptides. Through the analysis on the stability of various secondary structures of these peptides, it is demonstrated that the charge pattern is the basic reason of the different responses of the EAK16-family peptides to the environmental changes. These results provide some examples and insights for the principles of structural selection by environment and may be helpful for further analysis and designs of peptide systems.
肽的结构及其组装在很大程度上受到环境的调节。发现环境调节肽结构的物理原理对许多应用都将是有用的。作为典型例子，本文通过模拟研究了三种离子互补EAK16家族肽在各种环境条件下的结构。使用了具有中等分辨率的模型，其中明确考虑了主链氢键和静电相互作用。针对反映环境变化的各种静电相互作用强度，描述了这些肽的热力学（包括自由能和热容）。利用这些结果，给出并比较了这些肽与温度和静电相互作用强度相关的相图。基于肽相结构的差异，根据肽的单体结构特征解释了不同的聚集行为。通过对这些肽各种二级结构稳定性的分析，证明电荷模式是EAK16家族肽对环境变化产生不同响应的根本原因。这些结果为环境结构选择原理提供了一些实例和见解，可能有助于肽系统的进一步分析和设计。
