title: Water structures of differing order and mobility in aqueous solutions of schizophyllan, a triple-helical polysaccharide as revealed by dielectric dispersion measurements.
abstract: Dielectric dispersion measurements were made on aqueous solutions of a triple-helical polysaccharide schizophyllan over a wide concentration range 10-50 wt % at -45 to +30 degrees C. In the solution state, three different water structures with the different relaxation times tau were found, namely, bound water (taul), structured water (taus), and loosely structured water (tauls) in addition to free water (tauP). Structured water is less mobile and loosely structured water is nearly as mobile as free water, but bound water with taul is much less mobile, thus taul >> taus >> tauls greater, similar tauP. The order-disorder transition accompanies the conversion between structured water and loosely structured water. However, the species with taus remains even in the disordered state and constitutes part of bound water in the entire temperature range. In the frozen state, in addition to bulk water formed by partial melting, two mobile species existed, which were assigned to liquidlike bound water and found to be a continuation of bound water in the solution state. These relaxation time data are discussed in connection with the entropy levels of the four structures deduced from heat capacity data (cf. Yoshiba, K.; et al. Biomacromolecules 2003, 4, 1348-1356).
authors.affiliation: Research Organization of Science and Engineering and Department of Applied Chemistry, Faculty of Science and Engineering, Ritsumeikan University, Nojihigashi 1-1-1, Kusatsu, Siga 525-8577, Japan. kyoshiba@chem.sci.osaka-u.ac.jp
authors.forename: Kazuto
authors.initials: K
authors.lastname: Yoshiba
authors.forename: Akio
authors.initials: A
authors.lastname: Teramoto
authors.forename: Naotake
authors.initials: N
authors.lastname: Nakamura
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Shikata
authors.forename: Yuji
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: Michio
authors.initials: M
authors.lastname: Sorai
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Miura
mesh_terms: D000276:Adjuvants, Immunologic / Q000737:chemistry; D055592:Biophysical Phenomena; D001703:Biophysics; D004305:Dose-Response Relationship, Drug; D019277:Entropy; D006358:Hot Temperature; D046911:Macromolecular Substances / Q000737:chemistry*; D015233:Models, Statistical; D011134:Polysaccharides / Q000737:chemistry*; D012566:Sizofiran / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D013997:Time Factors; D014867:Water / Q000737:chemistry*
chemical_list: D000276:Adjuvants, Immunologic; D046911:Macromolecular Substances; D011134:Polysaccharides; D014867:Water; D012566:Sizofiran