Title : Site-specific characterization of
the N-linked oligosaccharides of a murine
immunoglobulin M by high-performance liquid chromatography/electrospray mass spectrometry
Abstract :
- Immunoglobulin M is an especially important product of the immune system because it plays a critical role in early protection against infections
- In this report, the glycosylation pattern of the protective murine monoclonal IgM 12A1 to Cryptococcus neoformans polysaccharide was analyzed by high-performance liquid chromatography coupled with electrospray ionization mass spectrometry
- Peptide mapping studies covering 88% of the deduced amino acid sequence indicated that of the six potential N-glycosylation sites in this antibody only five were utilized, as the tryptic peptide derived from monoclonal IgM 12A1 containing Asn-260 was recovered without carbohydrates
- The oligosaccharide side chains of monoclonal IgM 12A1 were characterized at each of the N-glycosylation sites
- Asn-166 possessed 20 monosialylated and nonsialylated, and fucosylated and nonfucosylated complex- and hybrid-type oligosaccharides and one high-mannose-type oligosaccharide.
- Thirteen oligosaccharides were attached to the site at Asn-401 , including six complex-type , four hybrid-type, and three high-mannose-type oligosaccharides.
- Twelve hybrid-type oligosaccharides were attached to Asn-378 , three of which had terminal sialic acids
- Eleven hybrid-type oligosaccharides were attached to Asn-331 , seven of which had terminal sialic acids
- Only two high-mannose type oligosaccharides were attached to Asn-363
- These results indicated great complexity in the structure and com position of oligosaccharides attached to individual IgM glycosylation sites