Isotope effect on the order-disorder transition in aqueous schizophyllan

✍ Scribed by Takashi Itou; Akio Teramoto; Takasuke Matsuo; Hiroshi Suga

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 941 KB
• Volume: 160
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(87)80315-4

✦ Synopsis

Optical rotation, heat capacity, and viscosity measurements were made on D,O solutions of schizophyllan, a triple-helical polysacchande.

Solutions of schizophyllan m D,O showed, at -290 K, an order-disorder transition which depended remarkably on the molecular weight of the sample. The transition closely resembled the helix-coil transitions of polypeptides, and it was concluded that it was a cooperative transition between the ordered and disordered states of the triple helix. It was found that (I) the triple helix is kept intact throughout the transition region, (2) the transition is extremely cooperative, (3) the mobility of side chains is restricted in the ordered state, (4) the helix diameter is larger in the ordered state than m the disordered state, and (5) the transition undergoes a remarkable isotope effect, suggesting that water molecules, as well as side chains, play an important role in the transition. All these findings were taken into account in order to propose possible organized structure formed about the helix core m the ordered state.