O-fucosylation of an antibody light chain: characterization of a modification occurring on an IgG1 molecule

Glycobiology. 2009 Feb;19(2):144-52. doi: 10.1093/glycob/cwn116. Epub 2008 Oct 24.


We describe the characterization of an O-fucosyl modification to a serine residue on the light chain of a recombinant, human IgG1 molecule expressed in Chinese hamster ovary (CHO) cells. Cation exchange chromatography (CEX) and hydrophobic interaction chromatography (HIC) were used to isolate a Fab population which was 146 Da heavier than the expected mass. Isolated Fab fragments were treated with a reducing agent to facilitate mass spectrometric analysis of the reduced light chain (LC) and fragment difficult (Fd). An antibody light chain with a net addition of 146 Da was detected by mass spectrometric analysis of the modified Fab. A light chain tryptic peptide in complementarity determining region-1 (CDR-1) was subsequently identified with a net addition of 146 Da by a peptide map. Results from a nanospray infusion of the modified peptide into a linear ion trap mass spectrometer with electron transfer dissociation (ETD) functionality indicated that the modified residue was a serine at position 30 in the light chain. Acid hydrolysis of the modified tryptic peptide followed by fluorescent labeling with 2-aminoanthranilic acid (2AA) and HPLC comparison with monosaccharide standards confirmed the presence of fucose on the light chain peptide. The presence of O-fucose on an antibody has not been previously reported. Currently, O-fucose has been described as occurring on mammalian proteins with amino acid sequence motifs associated with epidermal growth factor (EGF)-like repeats or thrombospondin type 1 repeats (TSRs). The amino acid sequence around the modified Ser in the IgG1 molecule does not conform to any known O-fucosylation sequence motif and thus is the first description of this type of modification on a nonconsensus sequence in a mammalian protein.

MeSH terms

  • Animals
  • Antibodies / chemistry
  • Antibodies / metabolism
  • CHO Cells
  • Cricetinae
  • Cricetulus
  • Fucose / metabolism*
  • Humans
  • Immunoglobulin G / chemistry*
  • Immunoglobulin G / metabolism
  • Immunoglobulin Light Chains / chemistry
  • Immunoglobulin Light Chains / metabolism*
  • Mass Spectrometry
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism


  • Antibodies
  • Immunoglobulin G
  • Immunoglobulin Light Chains
  • Recombinant Proteins
  • Fucose