title: Molecular thermodynamics of trifluoroethanol-induced helix formation: analysis of the solvation structure and free energy by the 3D-RISM theory.
abstract: It has been shown that trifluoroethanol (TFE) induces helical structure in peptides and proteins. The molecular mechanism is, however, still not completely elucidated. In this study, the TFE effects on the solvation structure and on the free energy change associated with the helix-coil transition of a polypeptide are analyzed by using the three-dimensional reference interaction site model (3D-RISM) molecular theory of solvation. The theoretical result shows that TFE preferentially solvates at low concentrations around 30 vol% both for the helix and coil structures. However, the characteristic preferential solvation is not as significant in the TFE-induced helix stabilization as generally considered. It is also found that the overall energy contributes to the free energy difference more substantially than the solvation entropy.
authors.affiliation: Computational Science Research Program, RIKEN, Wako, Saitama, 351-0112, Japan. takashi.imai@riken.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Imai
authors.forename: Andriy
authors.initials: A
authors.lastname: Kovalenko
authors.forename: Fumio
authors.initials: F
authors.lastname: Hirata
authors.forename: Akinori
authors.initials: A
authors.lastname: Kidera
mesh_terms: D000465:Algorithms; D001703:Biophysics / Q000379:methods; D003198:Computer Simulation; D019277:Entropy; D000431:Ethanol / Q000737:chemistry; D006860:Hydrogen Bonding; D000432:Methanol / Q000737:chemistry; D008962:Models, Theoretical; D008968:Molecular Conformation; D010455:Peptides / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013816:Thermodynamics; D014270:Trifluoroethanol / Q000737:chemistry*
chemical_list: D010455:Peptides; D012997:Solvents; D000431:Ethanol; D014270:Trifluoroethanol; D000432:Methanol