E.s.r. study of the conformational transition of spin-labelled xanthan gum in aqueous solution
| Autor: | Shoji Takigami, Peter A. Williams, Machiko Shimada, Glyn O. Phillips |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
Conformational change
Nitroxide mediated radical polymerization Aqueous solution Chemistry Osmolar Concentration Polysaccharides Bacterial Electron Spin Resonance Spectroscopy Molecular Conformation Temperature Ionic bonding General Medicine Biochemistry Solutions Crystallography Structural Biology Ionic strength medicine Side chain Organic chemistry Molecule Spin Labels Molecular Biology Xanthan gum medicine.drug |
| Zdroj: | International Journal of Biological Macromolecules. 15:367-371 |
| ISSN: | 0141-8130 |
| DOI: | 10.1016/0141-8130(93)90055-q |
| Popis: | The order to disorder transition of xanthan molecules in aqueous solutions has been studied using e.s.r. spectroscopy. Nitroxide spin-label was covalently attached to carboxyl groups on the xanthan side chains. The e.s.r. spectra obtained for aqueous spin-labelled xanthan solutions at varying ionic strengths contained both isotropic and anisotropic components at room temperature. The anisotropic component was attributed to the association of the side chains with the xanthan cellulosic backbone and was found to be present in greater proportions at increasing ionic strength. The spectra gradually changed with rising temperature and the proportion of anisotropic component decreased. This spectral change reflected the disruption of the side chain association with the backbone during the conformational change. Hysteresis effects were observed following sequential heating and cooling cycles suggesting that chain aggregation occurred. |
| Databáze: | OpenAIRE |
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