Characterization of a novel modification on IgG2 light chain. Evidence for the presence of O-linked mannosylation
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Updated: Jul 15, 2026

Characterization of Glycoproteins with the Immunoglobulin Fold by X-Ray Crystallography and Biophysical Techniques
Published on: July 5, 2018
Theresa Martinez1, Danielle Pace, Lowell Brady
1Analytical Sciences, Amgen Inc., 1201 Amgen Court West, Seattle, WA 98119, USA. martinet@amgen.com
Abstract:
This paper describes the analysis of a novel modification identified on the light chain of a recombinant IgG2 antibody. This modification, a +162 Da adduct, suggestive of a single hexose addition, was observed by mass analysis of the reduced molecule. The modification was located on residue serine 66 of the light chain by investigation with LC-MS peptide mapping, mass spectrometry and N-terminal sequencing techniques. Location of the adduct on serine pointed the investigation toward O-linked glycosylation. Identification of the hexose residue was deduced from its elimination by action of alpha-mannosidase, providing evidence for the presence of an O-mannosylated light chain. This type of modification in the glycosylation profile of antibodies, to our knowledge, has not been reported for human IgG molecules.
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