High resolution 13C-n.m.r. spectroscopy of ‘mixed linkage’ xylans
| Autor: | María C. Matulewicz, Alberto S. Cerezo, Ronald M. Jarret, Ny Syn |
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| Rok vydání: | 1992 |
| Předmět: |
Carbon Isotopes
Magnetic Resonance Spectroscopy Optical Rotation Chemistry Analytical chemistry Diad General Medicine Nuclear magnetic resonance spectroscopy Seaweed Biochemistry Spectral line Random coil Chemical bond Structural Biology Ionic strength Carbohydrate Conformation Xylans Optical rotation Spectroscopy Molecular Biology |
| Zdroj: | International Journal of Biological Macromolecules. 14:29-32 |
| ISSN: | 0141-8130 |
| DOI: | 10.1016/s0141-8130(05)80016-9 |
| Popis: | Three xylan fractions, obtained by stepwise precipitation with ethanol, were analysed by 75-MHz 13C-n.m.r. spectroscopy. Diad frequencies, determined from the C-2 resonances, show that the (1----3)-linkages are interspersed throughout the chain rather than grouped contiguously. This type of distribution is in agreement with a random coil conformation and with the constancy of the optical rotation in solvents of different ionic strength and chaotropic power. These diad frequencies were compared with the theoretical values calculated for a random distribution from the ratio of (1----4)-:(1----3)-linkages in the 1H-n.m.r. spectra, and from the methylation analysis for one of the fractions. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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