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Construction of First-Principle Methodology for Predicting Shape and Size Distribution of Micelles

预测胶束形状和尺寸分布的第一原理方法的构建

基本信息

批准号：
12640495
负责人：
KINOSHITA Masahiro
金额：
$ 2.69万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

Research for biological systems such as the prediction of tertiary structures of proteins, which is similar to the micelle research in the methodology and solvent effects, has also been performed.We have constructed a hybrid-type simulation method. It is a combination of the RISM theory (a statistical-mechanical theory for molecular fluids) for incorporating the solvent effects, the Monte Carlo simulated annealing for conformational sampling for a set of surfactant molecules, and a conventional thermodynamic method. It has been demonstrated for several simplified model surfactants to calculate the critical micelle concentration, micelle shape, and size distribution. It is being extended to more realistic models to elucidate why the average micelle size becomes larger as the temperature increases in cases of nonionic surfactants.We propose a simple. efficient bridge correction of the RISM theory. By combining the modified RISM method with the Kirkwood-Buff theory, the partial molar volume is calculated for the 20 amino acids and for oligopeptides of glutamic acids in extended and α-helix conformations. The bridge correction drastically improves agreement between the calculated values and the experimental data.The three-dimensional version of the integral equation theory is not applicable to the hybrid-type simulation method due to the heavy computational burden. However, it is very useful in detailed analyses of the microscopic solvation structure of a large, complicated solute molecule. As an example, we have examined the roles of the entropic excluded-volume effects in colloidal and biological systems. In particular, it has been shown that remarkably high selectivity arises in the lock and key steric interaction between macromolecules by the entropic excluded-volume effects alone.

在方法学和溶剂效应方面与胶束研究类似的蛋白质三级结构预测等生物体系的研究也在进行中，构建了混合型模拟方法。它是RISM理论（分子流体的热力学理论）结合溶剂效应，Monte Carlo模拟退火构象采样的一组表面活性剂分子，和一个传统的热力学方法的组合。它已被证明为几个简化的模型表面活性剂，计算临界胶束浓度，胶束形状和尺寸分布。它正在扩展到更现实的模型，以阐明为什么平均胶束尺寸变得更大的情况下，非离子表面活性剂的温度升高。RISM理论的有效桥梁修正。将改进的RISM方法与Kirkwood-Buff理论相结合，计算了20种氨基酸和谷氨酸寡肽在伸展构象和α-螺旋构象下的偏摩尔体积。桥修正大大提高了计算值与实验数据之间的一致性。由于计算量大，三维积分方程理论不适用于混合型模拟方法。然而，它是非常有用的详细分析的微观溶剂化结构的一个大的，复杂的溶质分子。作为一个例子，我们研究了熵排斥体积效应在胶体和生物系统中的作用。特别是，它已被证明，显着高的选择性出现在锁和关键的大分子之间的空间相互作用的熵排斥体积效应单独。