| Budget Amount *help |
¥4,200,000 (Direct Cost: ¥4,200,000)
Fiscal Year 2002: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 2001: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2000: ¥3,400,000 (Direct Cost: ¥3,400,000)
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| Research Abstract |
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.
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