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*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

15 Downloads (Pure)

Abstract

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.
Original languageEnglish
Pages (from-to)11900-11906
Number of pages7
JournalPCCP : Physical Chemistry Chemical Physics
Volume20
Early online date2021
DOIs
Publication statusPublished - 2021

Cite this