Measurement of inter-glycosidic 13C-1H coupling constants in a cyclic beta(1-->2)-glucan by 13C-filtered 2D (1H,1H)ROESY.
A method for measuring three-bond 13C-1H scalar coupling constants across glycosidic bonds in a cyclic beta(1-->2)-glucan icosamer is presented. This oligosaccharide molecule, with its high degree of symmetry, represents a particular challenge for NMR spectroscopy to distinguish inter-residue from intra-residue heteronuclear coupling effects. Chemically equivalent H2 protons in adjacent glucosyl residues are distinguished on the basis of their different through-space, dipolar interactions with the anomeric protons (H1). The strong NOE contact between anomeric (H1) and aglyconic (H2') protons permits the selective observation of the inter-residue heteronuclear couplings 3JC1H2' and 3JC2'H1 in a natural-abundance 13C-omega 1-half-filtered (1H,1H)ROESY experiment.
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Complex Carbohydrate Research Center, University of Georgia, Athens 30602.
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van Halbeek
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D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002247:Carbon Isotopes; D005936:Glucans / Q000737:chemistry* / Q000302:isolation & purification; D006859:Hydrogen; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008969:Molecular Sequence Data; D012231:Rhizobium; D047071:beta-Glucans
D002247:Carbon Isotopes; D005936:Glucans; D047071:beta-Glucans; C080135:cyclic beta(1-2)glucan; D006859:Hydrogen