Differentiation between isomeric triantennary N-linked glycans by negative ion tandem mass spectrometry and confirmation of glycans containing galactose attached to the bisecting (beta1-4-GlcNAc) residue in N-glycans from IgG

Rapid Commun Mass Spectrom. 2008 Apr;22(7):1047-52. doi: 10.1002/rcm.3470.


Negative ion tandem mass spectrometry (MS/MS) spectra of three isomeric triantennary N-linked glycans provided clear differentiation between the isomers and confirmed the occurrence of an isomer that was substituted with galactose on a bisecting GlcNAc (1 --> 4-substituted on the core mannose) residue recently reported by Takegawa et al. from N-glycans released from human immunoglobulin G (IgG). We extend this analysis of human serum IgG to reveal an analogue of the fucosylated triantennary glycan reported by Takegawa et al. together with a third compound that lacked both the sialic acid and the fucose residues. In addition, we demonstrate the biosynthesis of bisected hybrid-type glycans with the galactose modification, with and without core fucose, on the stem cell marker glycoprotein, 19A, expressed in a partially ricin-resistant human embryonic kidney cell line. It would appear, therefore, that this modification of N-linked glycans containing a galactosylated bisecting GlcNAc residue may be more common than originally thought. Negative ion MS/MS analysis of glycans is likely to prove an invaluable tool in the analysis and monitoring of therapeutic glycoproteins.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anions
  • Biomarkers, Tumor / chemistry*
  • Galactose / chemistry*
  • Immunoglobulin G / chemistry*
  • Isomerism
  • N-Acetylgalactosaminyltransferases
  • Oligopeptides / chemistry*
  • Polysaccharides / chemistry*
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Spectrometry, Mass, Electrospray Ionization
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods*


  • Anions
  • Biomarkers, Tumor
  • Immunoglobulin G
  • Oligopeptides
  • Polysaccharides
  • N-Acetylgalactosaminyltransferases
  • (N-acetylneuraminyl)-galactosylglucosylceramide N-acetylgalactosaminyltransferase
  • Galactose