Počet záznamů: 1
Tracking Isomerizations of High-Energy Adenine Cation Radicals by UV–Vis Action Spectroscopy and Cyclic Ion Mobility Mass Spectrometry
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SYSNO ASEP 0573880 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název Tracking Isomerizations of High-Energy Adenine Cation Radicals by UV–Vis Action Spectroscopy and Cyclic Ion Mobility Mass Spectrometry Tvůrce(i) Zima, V. (US)
Vlk, Mikuláš (UOCHB-X) ORCID
Wan, J. (US)
Cvačka, Josef (UOCHB-X) RID, ORCID
Tureček, F. (US)Zdroj.dok. Journal of Physical Chemistry A. - : American Chemical Society - ISSN 1089-5639
Roč. 127, č. 28 (2023), s. 5899-5913Poč.str. 15 s. Jazyk dok. eng - angličtina Země vyd. US - Spojené státy americké Klíč. slova photodissociation action spectroscopy ; basis-set convergence ; gas phase Obor OECD Analytical chemistry Způsob publikování Omezený přístup Institucionální podpora UOCHB-X - RVO:61388963 UT WOS 001033697600001 EID SCOPUS 85165519229 DOI 10.1021/acs.jpca.3c03179 Anotace We report experimental and computational studies of protonated adenine C-8 σ-radicals that are presumed yet elusive reactive intermediates of oxidative damage to nucleic acids. The radicals were generated in the gas phase by the collision-induced dissociation of C-8–Br and C-8–I bonds in protonated 8-bromo- and 8-iodoadenine as well as by 8-bromo- and 8-iodo-9-methyladenine. Protonation by electrospray of 8-bromo- and 8-iodoadenine was shown by cyclic-ion mobility mass spectrometry (c-IMS) to form the N-1-H, N-9-H and N-3-H, N-7-H protomers in 85:15 and 81:19 ratios, respectively, in accordance with the equilibrium populations of these protomers in water-solvated ions that were calculated by density functional theory (DFT). Protonation of 8-halogenated 9-methyladenines yielded single N-1-H protomers, which was consistent with their thermodynamic stability. The radicals produced from the 8-bromo and 8-iodo adenine cations were characterized by UV–vis photodissociation action spectroscopy (UVPD) and c-IMS. UVPD revealed the formation of C-8 σ-radicals along with N-3-H, N-7-H-adenine π-radicals that arose as secondary products by hydrogen atom migrations. The isomers were identified by matching their action spectra against the calculated vibronic absorption spectra. Deuterium isotope effects were found to slow the isomerization and increase the population of C-8 σ-radicals. The adenine cation radicals were separated by c-IMS and identified by their collision cross sections, which were measured relative to the canonical N-9-H adenine cation radical that was cogenerated in situ as an internal standard. Ab initio CCSD(T)/CBS calculations of isomer energies showed that the adenine C-8 σ-radicals were local energy minima with relative energies at 76–79 kJ mol–1 above that of the canonical adenine cation radical. Rice–Ramsperger–Kassel–Marcus calculations of unimolecular rate constants for hydrogen and deuterium migrations resulting in exergonic isomerizations showed kinetic shifts of 10–17 kJ mol–1, stabilizing the C-8 σ-radicals. C-8 σ-radicals derived from N-1-protonated 9-methyladenine were also thermodynamically unstable and readily isomerized upon formation. Pracoviště Ústav organické chemie a biochemie Kontakt asep@uochb.cas.cz ; Kateřina Šperková, Tel.: 232 002 584 ; Jana Procházková, Tel.: 220 183 418 Rok sběru 2024 Elektronická adresa https://doi.org/10.1021/acs.jpca.3c03179
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