Singlet O2 Reactions with Radical Cations of 8-Bromoguanine and 8-Bromoguanosine: Guided-Ion Beam Mass Spectrometric Measurements and Theoretical TreatmentsClick to copy article linkArticle link copied!
- Jonathan BennyJonathan BennyDepartment of Chemistry and Biochemistry, Queens College of the City University of New York, 65-30 Kissena Blvd., Queens, New York 11367, United StatesPh.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 5th Avenue, New York, New York 10016, United StatesMore by Jonathan Benny
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- Toru Saito*Toru Saito*Email: [email protected]Department of Biomedical Information Science, Graduate School of Information Science, Hiroshima City University, 3-4-1 Ozuka-Higashi, Asa-Minami-Ku, 731-3194 Hiroshima, JapanMore by Toru Saito
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- May Myat MoeMay Myat MoeDepartment of Chemistry and Biochemistry, Queens College of the City University of New York, 65-30 Kissena Blvd., Queens, New York 11367, United StatesPh.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 5th Avenue, New York, New York 10016, United StatesMore by May Myat Moe
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- Jianbo Liu*Jianbo Liu*Email: [email protected]. Phone: 1-718-997-3271.Department of Chemistry and Biochemistry, Queens College of the City University of New York, 65-30 Kissena Blvd., Queens, New York 11367, United StatesPh.D. Program in Chemistry, The Graduate Center of the City University of New York, 365 5th Avenue, New York, New York 10016, United StatesMore by Jianbo Liu
Abstract

8-Bromoguanosine is generated in vivo as a biomarker for early inflammation. Its formation and secondary reactions lead to a variety of biological sequelae at inflammation sites, most of which are mutagenic and linked to cancer. Herein, we report the formation of radical cations of 8-bromoguanine (8BrG•+) and 8-bromoguanosine (8BrGuo•+) and their reactions toward the lowest excited singlet molecular oxygen (1O2)─a common reactive oxygen species generated in biological systems. This work aims to investigate synergistic, oxidatively generated damage of 8-brominated guanine and guanosine that may occur upon ionizing radiation, one-electron oxidation, and 1O2 oxidation. Capitalizing on measurements of reaction product ions and cross sections of 8BrG•+ and 8BrGuo•+ with 1O2 using guided-ion beam tandem mass spectrometry and augmented by computational modeling of the prototype reaction system, 8BrG•+ + 1O2, using the approximately spin-projected ωB97XD/6-31+G(d,p) density functional theory, the coupled cluster DLPNO-CCSD(T)/aug-cc-pVTZ and the multireference CASPT2(21,15)/6-31G**, probable reaction products, and potential energy surfaces (PESs) were mapped out. 8BrG•+ and 8BrGuo•+ present similar exothermic oxidation products, and their reaction efficiencies with 1O2 increase with decreasing collision energy. Both single- and multireference theories predicted that the two most energetically favorable reaction pathways correspond to 1O2-addition to the C8 and C5-positions of 8BrG•+, respectively. The CASPT2-calculated PES represents the best quantitative agreement with the experimental benchmark, in that the oxidation exothermicity is close to the water hydration energy of product ions and, thus, is able to eliminate a water ligand in the product ions.
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This article is cited by 6 publications.
- May Myat Moe, Toru Saito, Midas Tsai, Jianbo Liu. Singlet O2 Oxidation of the Radical Cation versus the Dehydrogenated Neutral Radical of 9-Methylguanine in a Watson–Crick Base Pair. Consequences of Structural Context. The Journal of Physical Chemistry B 2022, 126
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- May Myat Moe, Midas Tsai, Jianbo Liu. Effects of Intra‐Base Pair Proton Transfer on Dissociation and Singlet Oxygenation of 9‐Methyl‐8‐Oxoguanine−1‐Methyl‐Cytosine Base‐Pair Radical Cations. ChemPhysChem 2023, 24
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