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Iota-carrageenan Oligosaccharides as Model Compounds for Structural Analysis of Iota-carrageenan by 13 C-NMR Spectroscopy

Iota-carrageenan Oligosaccharides as Model Compounds for Structural Analysis of Iota-carrageenan... Abstract C-NMR spectroscopy is a powerful tool for structural analysis of carrageenans, but the assignments for some of the carbon atoms in the repeating disaccharide have not been determined conclusively. lota-neocarratetraose sulfate and iota-neocarrahexaose sulfate, generated by enzymatic hydrolysis of iota-carrageenan, provided model compounds for determining the correct assignments of carbons in the repeat unit of the parent polymer. A comparison of integrated values of resonance peaks in the 13C-NMR spectra was used to assign peaks to carbons of the repeat units at the non-reducing and reducing extremities and the internal repeat unit of the iota-oligosaccharides. The correct assignments for C-2 of 3-O-ß-D-galactopyranosyl-4-sulfate and C-6 of 4-O-3,6-anhydro-a-D-galactopyranosyl-2-sulfate were obtained using a specialized NMR technique (distortionless enhancement by polarization transfer). Introduction Carrageenans are a spectrum of structurally related cell wall polysaccharides, extracted with water, from certain members of the Rhodophyceae (red algae). Carrageenans are composed of alternately al-»3, 1--»4 linked D-galactopyranose residues, and are classified according to substitutions (commonly ester sulfate and the 3,6-anhydrogalactopyranose form of the 4-linked residue) on a repeating disaccharide (Fig. 1) (Rees 1969, Percival 1978, McCandless and Craigie 1979). Carrageenans, and the structurally related agars, are well known for their ability to form thermo-reversible gels http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Botanica Marina de Gruyter

Iota-carrageenan Oligosaccharides as Model Compounds for Structural Analysis of Iota-carrageenan by 13 C-NMR Spectroscopy

Botanica Marina , Volume 28 (1) – Jan 1, 1985

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References (23)

Publisher
de Gruyter
Copyright
Copyright © 2009 Walter de Gruyter
ISSN
0006-8055
eISSN
1437-4323
DOI
10.1515/botm.1985.28.1.9
Publisher site
See Article on Publisher Site

Abstract

Abstract C-NMR spectroscopy is a powerful tool for structural analysis of carrageenans, but the assignments for some of the carbon atoms in the repeating disaccharide have not been determined conclusively. lota-neocarratetraose sulfate and iota-neocarrahexaose sulfate, generated by enzymatic hydrolysis of iota-carrageenan, provided model compounds for determining the correct assignments of carbons in the repeat unit of the parent polymer. A comparison of integrated values of resonance peaks in the 13C-NMR spectra was used to assign peaks to carbons of the repeat units at the non-reducing and reducing extremities and the internal repeat unit of the iota-oligosaccharides. The correct assignments for C-2 of 3-O-ß-D-galactopyranosyl-4-sulfate and C-6 of 4-O-3,6-anhydro-a-D-galactopyranosyl-2-sulfate were obtained using a specialized NMR technique (distortionless enhancement by polarization transfer). Introduction Carrageenans are a spectrum of structurally related cell wall polysaccharides, extracted with water, from certain members of the Rhodophyceae (red algae). Carrageenans are composed of alternately al-»3, 1--»4 linked D-galactopyranose residues, and are classified according to substitutions (commonly ester sulfate and the 3,6-anhydrogalactopyranose form of the 4-linked residue) on a repeating disaccharide (Fig. 1) (Rees 1969, Percival 1978, McCandless and Craigie 1979). Carrageenans, and the structurally related agars, are well known for their ability to form thermo-reversible gels

Journal

Botanica Marinade Gruyter

Published: Jan 1, 1985

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