Characterization of the neutral glycopeptides containing the structure α-L-fucopyranosyl-(1→3)-2-acetamido-2-deoxy-D-glucose from neuroblastoma cells

Abstract

Human tumor cells of neurectoderm origin contain a high proportion of α-L-fucosyl linkages were determined by high-resolution, 500-MHz, 1H-n.m.r. spectroscopy which gave signals characteristics for α-L-Fucp-(1→3)-D-GlcNAc residues these L-fucosyl residues. This was shown by use of a specific α-L-fucosidase from almond emulsin and a broad-spectrum α-L-fucosidase from rat testes. The exact α-L-fucosyl linkages were determined by high-resolution, 500-MHz, 1H-n.m.r. spectroscopy which gave signals characteristic for α-L-Fucp-(1→3)-D-GlcNAc residues linked to branches and for α-L-Fucp-(1→6)-D-GlcNAc residues linked to the core. More than 95% of the asparagine-linked GlcNAc residues were substituted with (1→6)-α-L-fucosyl groups. Further definition of the range of neutral glycopeptides was obtained with immobilized lectins. Binding to E-PHA-agarose suggested the presence of a β-D-mannopyranosyl residue substituted at O-4 by a 2-acetamido-2-deoxy-D-glucopyranosyl group. α-L-Fucp-(1→3)-GlcNAc interfered with this binding since removal of α-L-fucosyl groups by almond emulsin alpha-L-fucosidase increased the binding by 100%. These studies demonstrate the ability of a combination of high-resolution 1H-n.m.r., enzyme degradation, and lectin-binding affinities to delineate structural elements of small amounts of oligosaccharide residues.