Tracking Isomerizations of High-Energy Adenine Cation Radicals by UV–Vis Action Spectroscopy and Cyclic Ion Mobility Mass Spectrometry

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388963%3A_____%2F23%3A00573880" target="_blank" >RIV/61388963:_____/23:00573880 - isvavai.cz</a>

Alternative codes found

RIV/00216208:11310/23:10467981

Result on the web

<a href="https://doi.org/10.1021/acs.jpca.3c03179" target="_blank" >https://doi.org/10.1021/acs.jpca.3c03179</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/acs.jpca.3c03179" target="_blank" >10.1021/acs.jpca.3c03179</a>

Result language

angličtina

Original language name

Tracking Isomerizations of High-Energy Adenine Cation Radicals by UV–Vis Action Spectroscopy and Cyclic Ion Mobility Mass Spectrometry

Original language description

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.

Czech name

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Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10406 - Analytical chemistry

Project

—

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2023

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Journal of Physical Chemistry A

ISSN

1089-5639

e-ISSN

1520-5215

Volume of the periodical

127

Issue of the periodical within the volume

28

Country of publishing house

US - UNITED STATES

Number of pages

15

Pages from-to

5899-5913

UT code for WoS article

001033697600001

EID of the result in the Scopus database

2-s2.0-85165519229