Site-selective soft X-ray absorption as a tool to study protonation and electronic structure of gas-phase DNA

Xin Wang, Sivasudhan Rathnachalam, Klaas Bijlsma, Wen Li, Ronnie Hoekstra, Markus Kubin, Martin Timm, Bernd von Issendorff, Vicente Zamudio-Bayer, J. Tobias Lau, Shirin Faraji*, Thomas Schlathölter*

*Bijbehorende auteur voor dit werk

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The conformation and the electronic structure of gas-phase oligonucleotides depends strongly on the protonation site. 5’-d(FUAG) can either be protonated at the A-N1 or at the G-N7 position. We have stored protonated 5’-d(FUAG) cations in a cryogenic ion trap held at about 20 K. To identify the protonation site and the corresponding electronic structure, we have employed soft X-ray absorption spectroscopy at the nitrogen K-edge. The obtained spectra were interpreted by comparison to timedependent density functional theory calculations using a short-range exchange correlation functional. Despite the fact that guanine has a significantly higher proton affinity than adenine, the agreement between experiment and theory is better for the A-N1 protonated system. Furthermore, an inverse site sensitivity is observed in which the yield of the nucleobase fragments that contain the absorption site appears substantially reduced, which could be explained by non-statistical fragmentation processes, localized on the photoabsorbing nucleobase.
Originele taal-2English
Pagina's (van-tot)11900-11906
Aantal pagina's7
TijdschriftPCCP : Physical Chemistry Chemical Physics
Volume20
Vroegere onlinedatum2021
DOI's
StatusPublished - 2021

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