jz0c00041_si_001.pdf (137.03 kB)
Site-Selective Dissociation upon Sulfur L‑Edge X‑ray Absorption in a Gas-Phase Protonated Peptide
journal contribution
posted on 2020-01-30, 20:23 authored by Lucas Schwob, Simon Dörner, Kaan Atak, Kaja Schubert, Martin Timm, Christine Bülow, Vicente Zamudio-Bayer, Bernd von Issendorff, J. Tobias Lau, Simone Techert, Sadia BariSite-selective
dissociation induced by core photoexcitation of
biomolecules is of key importance for the understanding of radiation
damage processes and dynamics and for its promising use as “chemical
scissors” in various applications. However, identifying products
of site-selective dissociation in large molecules is challenging at
the carbon, nitrogen, and oxygen edges because of the high recurrence
of these atoms and related chemical groups. In this paper, we present
the observation of site-selective dissociation at the sulfur L-edge
in the gas-phase peptide methionine enkephalin, which contains only
a single sulfur atom. Near-edge X-ray absorption mass spectrometry
has revealed that the resonant S 2p → σ*C–S excitation of the sulfur contained in the methionine side chain
leads to site-selective dissociation, which is not the case after
core ionization above the sulfur L-edge. The prospects of such results
for the study of charge dynamics in biomolecular systems are discussed.