Chemical Synthesis of Residue-Selectively 13C and 2H Double-Isotope-Labeled Oligosaccharides as Chemical Probes for the NMR-Based Conformational Analysis of Oligosaccharides.

The conformational analysis of oligosaccharide is a fundamental issue in glycobiology. NMR measurements of atom-selectively 13C-labeled oligosaccharides have provided valuable information concerning their conformation, which would not be possible using nonlabeled oligosaccharides. The amount of accessible information from an atom-selectively labeled molecule, however, is limited. In this work, we report on the chemical synthesis of residue-selectively 13C- and 2H-labeled oligosaccharides and their use in conformational analysis. 1H NMR measurements of such double isotope-labeled compounds can provide a great deal of information on the dihedral angles across glycosidic linkages. We demonstrated this method in the conformational analyses of some linear and branched β(1,3)-glucan oligosaccharides.