Characterization of glycosylation sites for a recombinant IgG1 monoclonal antibody and a CTLA4-Ig fusion protein by liquid chromatography-mass spectrometry peptide mapping.

Liquid chromatography mass spectrometry (LC-MS) peptide mapping can be a versatile technique for characterizing protein glycosylation sites without the need to remove the attached glycans as in conventional oligosaccharide mapping methods. In this way, both N-linked and O-linked sites of glycosylation can each be directly identified, characterized, and quantified by LC-MS as intact glycopeptides in a single experiment. LC-MS peptide mapping of the individual glycosylation sites avoids many of the limitations of preparing and analyzing an entire pool of released N-linked oligosaccharides from all sites mixed together.