Cholesteric structure and order-disorder transition in aqueous solutions of schizophyllan, a triple-helical polysaccharide

Citation
A. Teramoto et al., Cholesteric structure and order-disorder transition in aqueous solutions of schizophyllan, a triple-helical polysaccharide, MOLEC CRYST, 365, 2001, pp. 1329-1336
Citations number
9
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Physical Chemistry/Chemical Physics
Volume
365
Year of publication
2001
Pages
1329 - 1336
Database
ISI
SICI code
Abstract
Cholesteric pitch (P=2 pi/ q(c)) was measured for aqueous solutions of a tr iple-helical polysaccharide schizophyllan as a function of temperature (T), concentration (c) and molecular weight (M-v), q(c) was substantially indep endent of M-v but changed with T and c. At higher temperatures, q(c) change d monotonously with T but showed a sudden decrease around 7-18 degreesC on lowering T, which was due to the order-disorder transition of aqueous schiz ophyllan.. The concentration dependence of q(c) for D2O solutions in the hi gh temperature disordered state is the same as that for H2O solutions, and interpreted theoretically using the threaded effective freely jointed chain model. On temperature jump experiments, q(c) did not follow immediately T, but changed with the time elapsed. The relaxation time tau (ch) was less t han a few minutes. Since the conformation of the triple helix follows T muc h faster than tau (ch), this relaxation comes from rotational diffusion of the triple helix.