Lamellar-Micellar Transitions in Surfactant-Phospholipid- Protein Mixtures

表面活性剂-磷脂-蛋白质混合物中的层状-胶束转变

• 批准号: 9206615
• 负责人: Anne Walter
• 金额: $ 11.7万
• 依托单位: Wright State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-09-01 至 1994-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9206615&HistoricalAwards=false
• 关键词: Lamellar; Micellar; Transitions; Surfactant; Phospholipid

Amphiphilic molecules dispersed in aqueous solution spontaneously assemble into structures thought to be defined by the size, shape and chemistry of the entire system. In the dilute region of the phase diagram, phospholipids and surfactants undergo a vesicle- micelle transition with increasing fraction of surfactant. Two types of micelle were observed recently, a cylindrical mixed micelle and small mixed micelles at higher surfactant levels. The phase behavior of phospholipids with surfactants at high water content will be examined to elucidate the process of structural transition in these mixed systems from a thermodynamic and kinetic perspective. The structures will be identified and the positions of the phase boundaries determined as a function of amphiphile chemistry and thermodynamic parameters (temperature, pressure). cylindrical mixed micelles and their formation from small mixed micelles or vesicles will be characterized by separation techniques, fluorescence probes sensitive to the differences between these structures, nuclear magnetic resonance, and the kinetics of the transition. Molecular packing models will be tested and the energetics of assembly will be calculated in order to improve the quantitative models to be applied when using amphiphiles to create, for example, biological model membranes, drug delivery systems, and protein crystals. %%% The focus of this study is a class of molecules called amphiphiles. The amphiphiles have two parts, an oily, nonpolar or hydrophobic end, and a polar, hydrophilic end. A special class of amphiphiles is the phospholipids which along with amphiphilic proteins make up the membranes that surround the biological unit of the cell. When amphiphiles are added to water, they self-assemble into clusters of molecules with the polar hydrophilic groups facing the water and the nonpolar hydrophobic groups clustered together in the center. The shape and size of these structures depends on the shape and relative concentrations of the molecules that compose them. This study will focus on the biological amphiphiles dispersed in water with a series of detergents that are used in biological studies. The goals are to describe the structural transitions that occur as the relative detergent concentration changes using electron microscopy and several spectroscopic techniques. Understanding these systems may have far-reaching consequences. Subtle changes in phospholipid structure are likely to regulate cell function. Although the temperature and pressure affect the characteristic properties of an amphiphiles - water system details are not well known. The general principles learned will have a broader application for all amphiphilic mixtures from detergent design to the rheology properties of mixture of oils and emulsifiers.

两亲分子在水溶液中自发分散 组装成被认为是由大小，形状， 和整个系统的化学反应。 在稀相区， 在相图中，磷脂和表面活性剂经历囊泡- 胶束转变与表面活性剂的分数增加。 两 最近观察到的胶束类型，一个圆柱形混合 胶束和小的混合胶束在较高的表面活性剂水平。 的 磷脂与表面活性剂在高水条件下的相行为 内容将被检查，以阐明结构的过程 在这些混合系统中，从热力学和动力学 perspective. 将确定结构和位置 作为两亲物的函数确定的相界 化学和热力学参数（温度、压力）。 圆柱形混合胶束及其由小混合胶束形成 胶束或囊泡的特征在于 技术，荧光探针敏感的差异， 这些结构之间，核磁共振， 过渡的动力学。 分子堆积模型将是 测试和组装的能量将被计算， 改进在使用时应用的定量模型， 两亲物来制造，例如，生物模型膜， 药物输送系统和蛋白质晶体。 %%% 这项研究的重点是一类被称为两亲分子的分子。 两亲物有两部分，油性，非极性或疏水性 末端和极性亲水末端。 一类特殊的两亲分子 是磷脂，它沿着两亲性蛋白质， 这些膜包围着细胞的生物单元。 当 两亲物被添加到水中，它们自组装成簇， 具有面向水的极性亲水基团的分子， 非极性疏水基团在中心聚集在一起。 这些结构的形状和尺寸取决于其形状和尺寸。 组成它们的分子的相对浓度。 本研究将集中在生物两亲分散在 水与一系列清洁剂，用于生物 问题研究 目标是描述结构性转变， 当相对洗涤剂浓度变化时， 电子显微镜和几种光谱技术。 了解这些系统可能会产生深远的影响。 磷脂结构的细微变化可能会调节 细胞功能 虽然温度和压力影响 两亲物-水体系的特性详情 并不广为人知。 学习的一般原则将有一个 用于洗涤剂中所有两亲性混合物的更广泛的应用 设计的流变性能的混合油和 乳化剂