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

• DOI: 10.1007/s13361-018-2035-6
• Publication Date: 2018-07-25T14:28:27Z
• Authors: Dmitrii Egorov; Sadia Bari; Rebecca Boll; Simon Dörner; Sascha Deinert; Simone Techert; Ronnie Hoekstra; Vicente Zamudio-B...; Rebecka Lindblad; Christine Bülow; Martin Timm; Bernd von Issendorff; J. Tobias Lau; Thomas Schlathölter
• Keywords: info:eu-repo/classification/ddc/530; Soft X ray spectroscopy, Soft X ray absorption, Photodissociation, Melittin, Protonated protein; 530; 01 natural sciences; 0104 chemical sciences

Journal of the American Society for Mass Spectrometry 29(11), 2138 - 2151 (2018). doi:10.1007/s13361-018-2035-6<br/>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 iontraps. 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 ionizationare 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.Keywords: Soft X-ray spectroscopy, Soft X-ray absorption, Photodissociation, Melittin, Protonated proteins<br/>Published by Springer, New York [u.a.]<br/>