An unambiguous assignment method by 2D selective-TOCSY-HSQC and selective-TOCSY-DQFCOSY and structural analysis by selective-TOCSY-NOESY experiments of a biantennary undecasaccharide

In this paper we present a newly developed 2D selective-TOCSY-HSQC experiment for unambiguous assignment of individual sugar components of a biantennary undecasaccharide. The correlation signals between the protons and carbons of a selectively excited sugar component in the undecasaccharide were observed in a 2D selective-TOCSY-HSQC experiment. The network of proton signals of this sugar was observed in a 2D selective-TOCSY-DQFCOSY experiment. These two experiments enabled us to perform unambiguous sequential assignment of both protons and carbons of the individual sugar components in the undecasaccharide. In addition, a three-dimensional structural analysis was performed by a 2D selective-TOCSY-NOESY experiment, which clearly distinguishes between inter-sugar and intra-sugar ring NOE signals.