STRUCTURES OF ASPARAGINE-LINKED OLIGOSACCHARIDES FROM HEN EGG-YOLK ANTIBODY (IGY) - OCCURRENCE OF UNUSUAL GLUCOSYLATED OLIGO-MANNOSE TYPE OLIGOSACCHARIDES IN A MATURE GLYCOPROTEIN

Asparagine-linked oligosaccharides present on hen egg-yolk immunoglobulin, termed IgY, were liberated from the protein by hydrazinolysis. After N-acetylation, the oligosaccharides were labelled with a UV-absorbing compound, p-aminobenzoic acid ethyl ester (ABEE). The ABEE-derivatized oligosaccharides were fractionated by anion exchange, normal phase and reversed phase HPLC, and their structures were determined by a combination of sugar composition analysis, methylation analysis, negative ion FAB-MS, 500 MHz H-1-NMR and sequential exoglycosidase digestions. IgY contained monoglucosylated oligomannose type oligosaccharides with structures of Glc-alpha-1-3Man7-9-GlcNAc-GlcNAc, oligomannose type oligosaccharides with the size range of Man5-9GlcNAc-GlcNAc, and biantennary complex type oligosaccharides with core region structure of Man-alpha-1-6(+/- GlcNAc-beta-1-4)(Man-alpha-1-3)Man-beta-1-4(+/-Fuc-alpha-1-6)GlcNAc. The glucosylated oligosaccharides, Glc1Man8GlcNAc2 and Glc1Man7GlcNAc2, have not previously been reported in mature glycoproteins from any source.