COMPUTER SIMULATION OF AMPHIPHILIC AGGREGATES

该提案要求提供支持，以调查 两亲性分子组装的计算机模拟 技巧。两亲性是带有极性头基的分子。 和碳氢化合物尾气。他们是肥皂剧的成分， 洗涤剂(脂肪酸)、细胞和模型生物膜 (磷脂)。在过去的十年里，计算机模拟已经 作为对真实实验的重要补充 对这种复杂系统的研究。建议使用现实主义 分子间势模型与分子动力学 用于研究组件的结构和动力学的计算 两亲性。特别强调的将是 烷基链的分子内结构(Guche/TRANS 异构化)和分子间链-链的性质 这些系统中的位置和方向关联。而当 长期目标是研究具有两种结构的磷脂 烷基链的初步工作将集中在脂肪的组装上 酸，每个头基团有一条链。具体的系统将是 分子动力学研究包括以下内容： A)负载的两亲性分子(脂肪酸)的单分子层 一种惰性衬底，如玻璃(朗缪尔-布洛杰特膜)。 B)载体上的两亲分子的单层和双层 烷基化玻璃基板(模型生物膜)。 C)空气/水中的两亲分子单层 界面(朗缪尔膜)。特别值得关注的是 所谓的凝胶阶段的特征，它发生在 单层的固化。 D)两亲分子在水中的准球形聚集体 溶液(胶束)和片状聚集体，重点是 头基溶剂化和链构象的性质。 最终目标是获得结构和动力 关于两亲性组装体行为的信息 补充了目前在芝加哥大学正在进行的实验 宾夕法尼亚州和其他地方的结构和功能 (模型)生物膜和相关系统。

This proposal asks for support to investigate the behavior of assemblies of amphiphilic molecules using computer simulation techniques. Amphiphiles are molecules with polar head groups and hydrocarbon tails. They are constituents of soaps and detergents (fatty acids), and cellular and model biomembranes (phospholipids). Over the past decade, computer simulation has emerged as an important complement to real experiments in the study of such complex systems. It is proposed to use realistic intermolecular potential models and molecular dynamics calculations to study the structure and dynamics of assemblies of amphiphiles. Particular emphasis will be placed on the intramolecular structure of the alkyl chains (gauche/trans isomerisation) and the nature of intermolecular chain-chain positional and orientational correlations in these systems. While the long-term objective is to study phospholipids which have two alkyl chains, the initial work will focus on assemblies of fatty acids with one chain per head group. The specific systems to be studied by molecular dynamics include the following: a) monolayers of amphiphilic molecules (fatty acids) supported on an inert substrate, such as glass (Langmuir-Blodgett films). b) monolayers and bilayers of amphiphilic molecules supported on an alkylated glass substrate (model biomembrane). c) monolayers of amphiphilic molecules at the air/water interface (Langmuir films). Of particular interest is the characterization of the so-called gel phase that occurs before the solidification of the monolayer. d) quasi-spherical aggregates of amphiphilic molecules in aqueous solution (micelles) and lamellar aggregates, with emphasis on the nature of the head group solvation and chain conformations. The eventual goal is to obtain structural and dynamical information on the behavior of amphiphilic assemblies that complements experiments currently underway at the University of Pennsylvania, and elsewhere, on the structure and function of (model) biomembranes and related systems.