Structures of asparagine-linked oligosaccharides of the glycoprotein fetuin having sialic acid linked to N-acetylglucosamine

In the accompanying paper (Bendiak et al., 1989), the separation of a series of oligosaccharides released from asparagine residues of fetuin was described. A series of NMR experiments, which included one- and two-dimensional nuclear Overhauser enhancement, two-dimensional correlation spectroscopy, and two-dimensional relayed-coherence spectroscopy, as well as permethylation analyses, established a Gal beta 1---3(NeuAc alpha 2---6)GlcNAc beta 1---4Man unit common to a series of purified structures. These oligosaccharides contained either three, four, or five glycosidically linked sialic acid residues. The NeuAc residue in alpha 2---6 linkage to GlcNAc gives rise to diagnostic chemical shift perturbations of particular proton signals in the oligosaccharides.