Abstract
Antibody sequence information is crucial to understanding the structural basis for antigen binding and enables the use of antibodies as therapeutics and research tools. Here, we demonstrate a method for direct de novo sequencing of monoclonal IgG from the purified antibody products. The method uses a panel of multiple complementary proteases to generate suitable peptides for de novo sequencing by liquid chromatography-tandem mass spectrometry (LC-MS/MS) in a bottom-up fashion. Furthermore, we apply a dual fragmentation scheme, using both stepped high-energy collision dissociation (stepped HCD) and electron-transfer high-energy collision dissociation (EThcD), on all peptide precursors. The method achieves full sequence coverage of the monoclonal antibody herceptin, with an accuracy of 99% in the variable regions. We applied the method to sequence the widely used anti-FLAG-M2 mouse monoclonal antibody, which we successfully validated by remodeling a high-resolution crystal structure of the Fab and demonstrating binding to a FLAG-tagged target protein in Western blot analysis. The method thus offers robust and reliable sequences of monoclonal antibodies.
Original language | English |
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Pages (from-to) | 3559-3566 |
Number of pages | 8 |
Journal | Journal of Proteome Research |
Volume | 20 |
Issue number | 7 |
Early online date | 14 Jun 2021 |
DOIs | |
Publication status | Published - 2 Jul 2021 |
Bibliographical note
Funding Information:Herceptin was a kind gift from Roche (Penzberg, Germany). The authors would like to acknowledge support by Protein Metrics Inc. through access to Supernovo software and helpful discussion on de novo antibody sequencing. The authors would like to thank everyone in the Biomolecular Mass Spectrometry and Proteomics group at Utrecht University for support and helpful discussions. This research was funded by the Dutch Research Council NWO Gravitation 2013 BOO, Institute for Chemical Immunology (ICI; 024.002.009).
Publisher Copyright:
© 2021 The Authors. Published by American Chemical Society
Keywords
- EThcD
- FLAG-tag
- anti-FLAG-M2
- antibody
- de novo sequencing
- herceptin
- mass spectrometry
- stepped HCD