Near-Edge Soft X-ray Absorption Mass Spectrometry of Protonated Melittin

Research output: Contribution to journalArticle


We have investigated the photoionization and photofragmentation yields of gas-phase multiply protonated melittin cations for photon energies at the K-shell absorption edges of carbon, nitrogen, and oxygen. Two similar experimental approaches were employed. In both experiments, mass selected [melittin+qH]q+ (q=2–4) ions were accumulated in radiofrequency ion traps. The trap content was exposed to intense beams of monochromatic soft X-ray photons from synchrotron beamlines and photoproducts were analyzed by means of time-of-flight mass spectrometry. Mass spectra were recorded for fixed photon energies, and partial ion yield spectra were recorded as a function of photon energy. The combination of mass spectrometry and soft X-ray spectroscopy allows for a direct correlation of protein electronic structure with various photoionization channels. Non-dissociative single and double ionization are used as a reference. The contribution of both channels to various backbone scission channels is quantified and related to activation energies and protonation sites. Soft X-ray absorption mass spectrometry combines fast energy deposition with single and double ionization and could complement established activation techniques. [Figure not available: see fulltext.].


  • Dmitrii Egorov
  • Sadia Bari
  • Rebecca Boll
  • Simon Dörner
  • Sascha Deinert
  • Simone Techert
  • Ronnie Hoekstra
  • Vicente Zamudio-Bayer
  • Rebecka Lindblad
  • Christine Bülow
  • Martin Timm
  • Bernd von Issendorff
  • J. Tobias Lau
  • Thomas Schlathölter
External organisations
  • University of Groningen
  • German Electron Synchrotron (DESY)
  • University of Göttingen
  • Albert-Ludwigs University Freiburg
  • Technical University of Berlin
  • Helmholtz-Zentrum Berlin for Materials and Energy
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Atom and Molecular Physics and Optics


  • Melittin, Photodissociation, Protonated proteins, Soft X-ray absorption, Soft X-ray spectroscopy
Original languageEnglish
Pages (from-to)2138-2151
Number of pages14
JournalJournal of the American Society for Mass Spectrometry
Issue number11
Publication statusPublished - 2018
Publication categoryResearch