Structure determination of a sulfated N-glycans, candidate for a precursor of the selectin ligand in bovine lung

To clarify the structure of non-sialic acid anionic residue on N-glycans in the mammalian tissues, we have isolated sialidase-resistant anionic residue on N-glycans from bovine lung. Analyses by partial acid hydrolysis and glycosidase digestions combined with a two-dimensional HPLC mapping method revealed that the major sialidase-resistant anionic N-glycan had a fucosylbianntenary core structure. The anionic residue was identified as a sulfate ester by methanolysis, anion-exchange chromatography, and mass spectrometry. The linkage position of the sulfate ester was the 6-position of the GlcNAc residue on the Manα1-6 branch. This conclusion was based on the results of glycosidase digestions followed by two-dimensional HPLC mapping. Furthermore, the disialylated form of this sulfated glycan was dominant, and no asialo form was detected. The structure of the major anionic N-glycan prepared from bovine lung and having a sulfate was proposed to be the pyridylamino derivative of Siaα2-3Gαlβ1-4(HSO₃-6)GlcNAcβ1-2Manα1-6(Siaα2-3Galβ1-4GlcNAcβ1-2Manα1-3)Manβ1-4GlcNAcβ1-4(Fucα1-6)GlcNAc.