Solution-phase deuterium/hydrogen exchange at a specific residue using nozzle-skimmer and electron capture dissociation mass spectrometry

Authors

  • Charlotte Hagman,

    Corresponding author
    1. Department of Engineering Sciences, Division of Ion Physics, Uppsala University, Uppsala, Box 534 S-751 21, Sweden
    Current affiliation:
    1. Novartis Institutes for Biomedical Research, CH-4002 Basel, Switzerland.
    • Novartis Institutes for Biomedical Research, CH-4002 Basel, Switzerland.
    Search for more papers by this author
  • Yury O. Tsybin,

    1. Ion Cyclotron Resonance Program, National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA
    Search for more papers by this author
  • Per Håkansson

    1. Department of Engineering Sciences, Division of Ion Physics, Uppsala University, Uppsala, Box 534 S-751 21, Sweden
    Search for more papers by this author

Abstract

Information about protein conformation can be obtained with hydrogen/deuterium exchange (HDX) mass spectrometry. The isotopic solution-phase exchange of specific amide hydrogen atoms can be followed using low-vacuum nozzle-skimmer collision-induced dissociation (CID). In this study, the nozzle-skimmer technique was complemented by electron capture dissociation (ECD) Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS). The solution-phase exchange at a specific residue is monitored by comparing isotopic distributions of two consecutive b- or c-type ions. While nozzle-skimmer fragmentation takes place in the low-vacuum region of the mass spectrometer, ECD occurs at ultra-high vacuum within the mass analyzer cell of the FTICR mass spectrometer. The dissociations take place at 10−4 and 10−9 mbar, respectively. Low-vacuum nozzle-skimmer fragmentation can result in intramolecular exchange between product ions and solvent molecules in the gas phase. Consequently, the solution-phase information about protein or peptide conformation is lost. It was not possible to monitor isotopic solution-phase exchange at the eighth residue in substance P, (Phe)8, with nozzle-skimmer CID. By using the in-cell ECD fragmentation method, the solution-phase exchange at the (Phe)8 residue was preserved during mass spectrometric analysis. This result shows the complementary aspects of applying fragmentation at low and at high vacuum, when studying isotopic exchange in solution at specific residues using FTICRMS. Copyright © 2006 John Wiley & Sons, Ltd.

Ancillary