Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706, USA.
J Chem Phys. 2010 Feb 14;132(6):065103. doi: 10.1063/1.3314309.
The sequence-directed self-assembly of amphiphilic beta-peptides is studied using Monte Carlo simulations. A phenomenological model is employed where each molecule is modeled as a rigid nanorod with side groups located at positions to mimic globally amphiphilic (GA) and nonglobally amphiphilic (non-GA) isomers of beta-peptides. The strength and the range of interactions between side groups are chosen based on the types of residues. The simulations show that the aggregation of beta-peptides is sensitive to the sequence and the residue types. For one type of beta-peptide the GA isomer has a greater tendency to aggregate while for the other the non-GA isomer has a greater tendency to aggregate. The trends observed in the simulations are consistent with recent experiments [Pomerantz et al., J. Am. Chem. Soc. 128, 8730 (2006); Pomerantz et al., Angew. Chem., Int. Ed. 47, 1 (2008)], although the molecules do not spontaneously form the hollow fibers seen in experiment. Simulations with initial configurations as hollow fibers show that the stability of the fibers follows the same trend as the tendency for aggregation. The simulations demonstrate that the details matter: the self-assembly of the molecules is sensitive to the strength of the short-ranged interactions and the size of the side groups, in addition to the global amphiphilicity of the molecules. This suggests the possibility of designing molecules for desired nanostructures.
使用蒙特卡罗模拟研究了两亲性β-肽的序列导向自组装。采用了一种唯象模型，其中每个分子都被建模为具有侧基的刚性纳米棒，其位置模拟了具有全局两亲性（GA）和非全局两亲性（non-GA）的β-肽异构体。侧基之间相互作用的强度和范围是根据残基的类型选择的。模拟表明，β-肽的聚集对序列和残基类型敏感。对于一种β-肽，GA 异构体具有更大的聚集倾向，而对于另一种异构体，non-GA 异构体具有更大的聚集倾向。模拟中观察到的趋势与最近的实验一致[Pomerantz 等人，J. Am. Chem. Soc. 128, 8730（2006）；Pomerantz 等人，Angew. Chem.，Int. Ed. 47, 1（2008）]，尽管这些分子不会自发形成实验中看到的中空纤维。具有初始中空纤维构型的模拟表明，纤维的稳定性遵循与聚集趋势相同的趋势。模拟表明细节很重要：分子的自组装对短程相互作用的强度和侧基的大小敏感，除了分子的全局两亲性之外。这表明有可能设计出具有所需纳米结构的分子。
