Characterization of a novel modification on IgG2 light chain. Evidence for the presence of O-linked mannosylation.
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.
Martinez
Theresa
T
Analytical Sciences, Amgen Inc., 1201 Amgen Court West, Seattle, WA 98119, USA. martinet@amgen.com
Pace
Danielle
D
Brady
Lowell
L
Gerhart
Mary
M
Balland
Alain
A
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000737:chemistry*; D006031:Glycosylation; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry*; D008358:Mannose / Q000737:chemistry*; D011994:Recombinant Proteins / Q000737:chemistry*; D012694:Serine / Q000737:chemistry; D043323:alpha-Mannosidase / Q000378:metabolism
D000911:Antibodies, Monoclonal; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D012694:Serine; D043323:alpha-Mannosidase; D008358:Mannose