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Ordering in aqueous polysaccharide solutions. I. Dielectric relaxation in aqueous solutions of a triple‐helical polysaccharide schizophyllan
Author(s) -
Hayashi Yoshihito,
Shinyashiki Naoki,
Yagihara Shin,
Yoshiba Kazuto,
Teramoto Akio,
Nakamura Naotake,
Miyazaki Yuji,
Sorai Michio,
Wang Qi
Publication year - 2002
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1059
Subject(s) - chemistry , aqueous solution , dispersion (optics) , relaxation (psychology) , bound water , dielectric , analytical chemistry (journal) , side chain , crystallography , chromatography , organic chemistry , polymer , molecule , materials science , optics , psychology , social psychology , physics , optoelectronics
Abstract Deuterium oxide solutions of a triple‐helical polysaccharide schizophyllan, undergoing an order–disorder transition centered around 17°C, were studied by the time‐domain reflectometry (TDR) to obtain dielectric dispersions in the solution and frozen states. In the solution state, the dispersion below the transition temperature is resolved in three dispersions (relaxation times at 0°C) ascribed to side chain glucose residue (1; 102 ns), structured water (s; 2.0 ns) and bulk water (h), respectively, from low to high frequencies. Bulk water is divided into slow water (h 2 ; 0.04 ns) and free or pure water (h 1 ; 0.02 ns). Above the transition temperature structured water almost disappears and is compensated by slow water. Structured water is similar to bound water for proteins but different from it because of this transition behavior. Another dispersion (l) seen at the lowest frequency is assigned to the rotation of side‐chain glucose residue coupled with hydrated water. Parts of this dispersion and structured water are suggested to constitute bound water. In the frozen state were observed a major dispersion (h; 0.14 ns) and a minor one (m; 28 ns), which were ascribed to considerably mobile and less mobile waters. They are similar to but not exactly the same as that for unfreezable water in bovine serum albumin solutions argued by Miura et al. ( Biopolymers, 1995, Vol. 36, p. 9). Water is molded into different structures by the triple helix. © 2002 John Wiley & Sons, Inc. Biopolymers 63: 21–31, 2002