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

Dmitrii Egorov, Sadia Bari, Rebecca Boll, Simon Dörner, Sascha Deinert, Simone Techert, Romke Hoekstra, Vicente Zamudio-bayer, Rebecka Lindblad, Christine Bülow, Martin Timm, Bernd Von Issendorf, J. Tobias Lau, Thomas Schlathölter

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Abstract

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.
Original languageEnglish
Pages (from-to)2138-2151
JournalJournal of the American Society for Mass Spectrometry
Volume29
DOIs
Publication statusPublished - Nov-2018

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