Fast analysis of recombinant monoclonal antibodies using IdeS proteolytic digestion and electrospray mass spectrometry.

We describe a fast and informative method to investigate the posttranslational modifications of monoclonal antibodies (MAbs). The MAb is first digested by a specific enzyme that cleaves heavy chains under the hinge domain. After reduction of disulfide bridges, three polypeptide chains of approximately 25 kDa are released and analyzed by liquid chromatography-mass spectrometry (LC-MS). By bisecting the heavy chains prior to MS analysis, this method provides a better MS resolution and facilitates the study of the N-linked glycans as well as of other modifications (loss of C-terminal lysine, pyroglutamination, and oxidation). The sample preparation and analysis can be performed within few hours.