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Hydrogen/deuterium exchange mass spectrometry with improved electrochemical reduction enables comprehensive epitope mapping of a therapeutic antibody to the cysteine-knot containing vascular endothelial growth factor

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  • Gerard Comamala
  • Cornelia Wagner
  • Pablo Sanz de la Torre
  • Rasmus U Jakobsen
  • Maximiliane Hilger
  • Hendrik-Jan Brouwer
  • Rand, Kasper Dyrberg

Hydrogen/deuterium exchange mass spectrometry (HDX-MS) has become a popular method for analysis of the conformational dynamics and interactions of proteins. Disulfide-bonded proteins, however, present a challenge to HDX-MS as they require efficient disulfide bond reduction prior to enzymatic proteolysis. Electrochemical reduction (ER) provides an attractive solution to tackle disulfide-bonded proteins that are resistant to conventional chemical reduction during HDX-MS. However, ER-enabled HDX-MS has been limited by technical challenges including partial unwanted protein oxidation side-reactions, incompatibility with certain buffer components and most importantly, a lack of overall method robustness. In this study, we have sought to address these challenges. We perform a systematic screening of the compatibility of ER to buffers commonly used in HDX-MS samples by using a reliable and simple system suitability test (SST). Furthermore, we demonstrate the benefits of a new design of the electrochemical cell (EC) for ER-enabled HDX-MS, which include a) high repeatability and robustness over large sample batches without the need for electrode polishing and b) high reduction efficiency of disulfide-bonded proteins without unwanted oxidation side-reactions. We show the real-world applicability of the optimized ER-enabled HDX-MS workflow by performing an epitope mapping of a Fab fragment of a therapeutic monoclonal antibody (mAb) to the cysteine knot-containing vascular endothelial growth factor (VEGF). The results allow us to comprehensively map sites in VEGF involved in mAb binding. Overall, our findings show how ER and HDX-MS can be combined to enable analysis of the conformation and interactions of challenging disulfide-rich proteins.

OriginalsprogEngelsk
TidsskriftAnalytica Chimica Acta
Vol/bind1115
Sider (fra-til)41-51
Antal sider11
ISSN0003-2670
DOI
StatusUdgivet - 8 jun. 2020

ID: 240836808