Complex glycosylation patterns containing multiantennary N-glycans are typically found in mature glycoproteins. However, the structural characterization of these glycans is rather challenging. Usually, standard NMR and X-ray diffraction techniques fail to provide specific answers on the structure and molecular recognition features due to intrinsic attributes of the glycan. As a promising approach, carbohydrates conjugated to lanthanide binding tags have revealed high potential toward this aim. This methodology has first been applied to the study of small oligosaccharides (di-, tri- and tetrasaccharides). [1-3] Proceeding from this experimental basis, we have extended this concept to the level of high degree branching and long chain N-glycans. The unprecedented resolution obtained in the spectra has allowed us to perform conformational and interaction analysis of complex carbohydrates such as: tetraantennary N-glycans and a sialylated tetradecasaccharide N-glycan presenting two LacNAc repetitions at each arm. [4-5] The latter is especially relevant since it has been identified as the receptor of the hemagglutinin protein of pathogenic influenza viruses. 
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