Site-specific characterization of the N-linked oligosaccharides of a murine immunoglobulin M by high-performance liquid chromatography/electrospray mass spectrometry

Fang Wang, Antonio Nakouzi, Ruth Hogue Angeletti, Arturo Casadevall

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28 Scopus citations


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 composition of oligosaccharides attached to individual IgM glycosylation sites.

Original languageEnglish (US)
Pages (from-to)266-280
Number of pages15
JournalAnalytical Biochemistry
Issue number2
Publication statusPublished - Mar 15 2003



  • Glycoprotein
  • Glycosylation
  • Monoclonal immunoglobulin M
  • N-linked oligosaccharides

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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