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Tackling a Curious Case: Generation of Charge-Tagged Guanosine Radicals by Gas-Phase Electron Transfer and Their Characterization by UV-vis Photodissociation Action Spectroscopy and Theory
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SYSNO ASEP 0541313 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název Tackling a Curious Case: Generation of Charge-Tagged Guanosine Radicals by Gas-Phase Electron Transfer and Their Characterization by UV-vis Photodissociation Action Spectroscopy and Theory Tvůrce(i) Liu, Y. (US)
Ma, C. (US)
Leonen, C. J. A. (US)
Chatterjee, C. (US)
Nováková, Gabriela (UOCHB-X) ORCID
Marek, Aleš (UOCHB-X) RID, ORCID
Tureček, F. (CZ)Zdroj.dok. Journal of the American Society for Mass Spectrometry. - : American Chemical Society - ISSN 1044-0305
Roč. 32, č. 3 (2021), s. 772-785Poč.str. 14 s. Jazyk dok. eng - angličtina Země vyd. US - Spojené státy americké Klíč. slova atoms ; biomolecules ; crown ethers Obor OECD Analytical chemistry CEP LTAUSA19094 GA MŠMT - Ministerstvo školství, mládeže a tělovýchovy Způsob publikování Omezený přístup Institucionální podpora UOCHB-X - RVO:61388963 UT WOS 000626328700020 EID SCOPUS 85101570201 DOI 10.1021/jasms.0c00459 Anotace We report the generation of gas-phase riboguanosine radicals that were tagged at ribose with a fixed-charge 6-(trimethylammonium)hexane-1-aminocarbonyl group. The radical generation relied on electron transfer from fluoranthene anion to noncovalent dibenzocrown-ether dication complexes which formed nucleoside cation radicals upon one-electron reduction and crown-ether ligand loss. The cation radicals were characterized by collision-induced dissociation (CID), photodissociation (UVPD), and UV-vis action spectroscopy. Identification of charge-tagged guanosine radicals was challenging because of spontaneous dissociations by loss of a hydrogen atom and guanine that occurred upon storing the ions in the ion trap without further excitation. The loss of H proceeded from an exchangeable position on N-7 in guanine that was established by deuterium labeling and was the lowest energy dissociation of the guanosine radicals according to transition-state energy calculations. Rate constant measurements revealed an inverse isotope effect on the loss of either hydrogen or deuterium with rate constants kH = 0.25-0.26 s-1 and kD = 0.39-0.54 s-1. We used time-dependent density functional theory calculations, including thermal vibronic effects, to predict the absorption spectra of several protomeric radical isomers. The calculated spectra of low-energy N-7-H guanine-radical tautomers closely matched the action spectra. Transition-state-theory calculations of the rate constants for the loss of H-7 and guanine agreed with the experimental rate constants for a narrow range of ion effective temperatures. Our calculations suggest that the observed inverse isotope effect does not arise from the isotope-dependent differences in the transition-state energies. Instead, it may be caused by the dynamics of post-transition-state complexes preceding the product separation. Pracoviště Ústav organické chemie a biochemie Kontakt asep@uochb.cas.cz ; Kateřina Šperková, Tel.: 232 002 584 ; Viktorie Chládková, Tel.: 232 002 434 Rok sběru 2022 Elektronická adresa https://doi.org/10.1021/jasms.0c00459
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