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Masi A, Capobianco A, Bobrowski K, Peluso A, Chatgilialoglu C. Hydroxyl Radical vs. One-Electron Oxidation Reactivities in an Alternating GC Double-Stranded Oligonucleotide: A New Type Electron Hole Stabilization. Biomolecules 2023; 13:1493. [PMID: 37892175 PMCID: PMC10605094 DOI: 10.3390/biom13101493] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2023] [Revised: 09/30/2023] [Accepted: 10/04/2023] [Indexed: 10/29/2023] Open
Abstract
We examined the reaction of hydroxyl radicals (HO•) and sulfate radical anions (SO4•-), which is generated by ionizing radiation in aqueous solutions under anoxic conditions, with an alternating GC doubled-stranded oligodeoxynucleotide (ds-ODN), i.e., the palindromic 5'-d(GCGCGC)-3'. In particular, the optical spectra of the intermediate species and associated kinetic data in the range of ns to ms were obtained via pulse radiolysis. Computational studies by means of density functional theory (DFT) for structural and time-dependent DFT for spectroscopic features were performed on 5'-d(GCGC)-3'. Comprehensively, our results suggest the addition of HO• to the G:C pair moiety, affording the [8-HO-G:C]• detectable adduct. The previous reported spectra of one-electron oxidation of a variety of ds-ODN were assigned to [G(-H+):C]• after deprotonation. Regarding 5'-d(GCGCGC)-3' ds-ODN, the spectrum at 800 ns has a completely different spectral shape and kinetic behavior. By means of calculations, we assigned the species to [G:C/C:G]•+, in which the electron hole is predicted to be delocalized on the two stacked base pairs. This transient species was further hydrated to afford the [8-HO-G:C]• detectable adduct. These remarkable findings suggest that the double-stranded alternating GC sequences allow for a new type of electron hole stabilization via delocalization over the whole sequence or part of it.
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Affiliation(s)
- Annalisa Masi
- Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, 40129 Bologna, Italy;
| | - Amedeo Capobianco
- Dipartimento di Chimica e Biologia “A. Zambelli”, Università di Salerno, 84084 Fisciano, Italy; (A.C.); (A.P.)
| | - Krzysztof Bobrowski
- Centre of Radiation Research and Technology, Institute of Nuclear Chemistry and Technology, 03-195 Warsaw, Poland;
| | - Andrea Peluso
- Dipartimento di Chimica e Biologia “A. Zambelli”, Università di Salerno, 84084 Fisciano, Italy; (A.C.); (A.P.)
| | - Chryssostomos Chatgilialoglu
- Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche, 40129 Bologna, Italy;
- Center for Advanced Technologies, Adam Mickiewicz University, 61-614 Poznań, Poland
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2
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Adjei D, Reyes Y, Kumar A, Ward S, Denisov SA, Alahmadi M, Sevilla MD, Wnuk SF, Mostafavi M, Adhikary A. Pathways of the Dissociative Electron Attachment Observed in 5- and 6-Azidomethyluracil Nucleosides: Nitrogen (N 2) Elimination vs Azide Anion (N 3-) Elimination. J Phys Chem B 2023; 127:1563-1571. [PMID: 36780335 PMCID: PMC9984991 DOI: 10.1021/acs.jpcb.2c08257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023]
Abstract
5-Azidomethyl-2'-deoxyuridine (5-AmdU, 1) has been successfully employed for the metabolic labeling of DNA and fluorescent imaging of live cells. 5-AmdU also demonstrated significant radiosensitization in breast cancer cells via site-specific nitrogen-centered radical (π-aminyl (U-5-CH2-NH•), 2, and σ-iminyl (U-5-CH═N•), 3) formation. This work shows that these nitrogen-centered radicals are not formed via the reduction of the azido group in 6-azidomethyluridine (6-AmU, 4). Radical assignments were performed using electron spin resonance (ESR) in supercooled solutions, pulse radiolysis in aqueous solutions, and theoretical (DFT) calculations. Radiation-produced electron addition to 4 leads to the facile N3- loss, forming a stable neutral C-centered allylic radical (U-6-CH2•, 5) through dissociative electron attachment (DEA) via the transient negative ion, TNI (U-6-CH2-N3•-), in agreement with DFT calculations. In contrast, TNI (U-5-CH2-N3•-) of 1, via facile N2 loss (DEA) and protonation from the surrounding water, forms radical 2. Subsequently, 2 undergoes rapid H-atom abstraction from 1 and produces the metastable intermediate α-azidoalkyl radical (U-5-CH•-N3). U-5-CH•-N3 converts facilely to radical 3. N3- loss from U-6-CH2-N3•- is thermodynamically controlled, whereas N2 loss from U-5-CH2-N3•- is dictated by protonation from the surrounding waters and resonance conjugation of the azidomethyl side chain at C5 with the pyrimidine ring.
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Affiliation(s)
- Daniel Adjei
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay; 91405, Orsay, Cedex, France
| | - Yahaira Reyes
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA
| | - Anil Kumar
- Department of Chemistry, 146 Library Drive, Oakland University, Rochester, Michigan 48309, USA
| | - Samuel Ward
- Department of Chemistry, 146 Library Drive, Oakland University, Rochester, Michigan 48309, USA
| | - Sergey A. Denisov
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay; 91405, Orsay, Cedex, France
| | - Moaadh Alahmadi
- Department of Chemistry, 146 Library Drive, Oakland University, Rochester, Michigan 48309, USA
| | - Michael D. Sevilla
- Department of Chemistry, 146 Library Drive, Oakland University, Rochester, Michigan 48309, USA
| | - Stanislaw F. Wnuk
- Department of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, USA
| | - Mehran Mostafavi
- Institut de Chimie Physique, UMR 8000 CNRS, Bât. 349, Université Paris-Saclay; 91405, Orsay, Cedex, France
| | - Amitava Adhikary
- Department of Chemistry, 146 Library Drive, Oakland University, Rochester, Michigan 48309, USA
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3
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Mohammadtabar F, Rajaie Khorasani R, Mohammadi-Manesh H, Kazempour A. Study of optical absorption cross-section spectra and high-order harmonic generation of thymine, thymine glycol, and thymine dimer molecules. J Mol Model 2022; 28:402. [DOI: 10.1007/s00894-022-05388-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 11/09/2022] [Indexed: 11/29/2022]
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4
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Kumar A, Sevilla MD. Proton-Transfer Reactions in One-Electron-Oxidized G-Quadruplexes: A Density Functional Theory Study. J Phys Chem B 2022; 126:1483-1491. [PMID: 35152699 PMCID: PMC8881324 DOI: 10.1021/acs.jpcb.1c10529] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Recently, G-quadruplexes (Gq) formed in B-DNA as secondary structures are found to be important therapeutic targets and material for developing nanodevices. Gq are guanine-rich and thus susceptible to oxidative damage by producing short-lived intermediate radicals via proton-transfer reactions. Understanding the mechanisms of radical formation in Gq is of fundamental interest to understand the early stages of DNA damage. Herein, we used density functional theory including aqueous phase (ωB97XD-PCM/6-31++G**) and considered single layer of Gq [G-quartets (G4): association of four guanines in a cyclic Hoogsteen hydrogen-bonded arrangement (Scheme 1)] to unravel the mechanisms of formation of intermediates by calculating the relative Gibbs free energies and spin density distributions of one-electron-oxidized G4 and its various proton-transfer states: G•+, G(N1-H)•, G(N2-H')•, G(N2-H″)•, G(N1-H)•-(H+O6)G, and G(N2-H)•-(H+N7)G. The present calculation predicts the formation of G(N2-H)•-(H+N7)G, which is only ca. 0.8 kcal/mol higher in energy than the initially formed G•+. The formation of G(N2-H)•-(H+N7)G plays a key role in explaining the formation of 8-OG along with G(N1-H)• formation via tautomerization from G(N2-H)•, as proposed recently.
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Affiliation(s)
- Anil Kumar
- Corresponding Author: . Tel: +1 248 370 2327, . Tel: +1 248 370 2328
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Khalili F, Vafaee M, Shokri B. Attosecond charge migration following oxygen K-shell ionization in DNA bases and base pairs. Phys Chem Chem Phys 2021; 23:23005-23013. [PMID: 34611693 DOI: 10.1039/d1cp02920g] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Core ionization of DNA begins a cascade of events which could lead to cellular inactivation or death. The created core-hole following an impulse inner-shell ionization of molecules naturally decays in the auger timescale. We simulated charge migration (CM) phenomena following an impulsive core ionization of individual DNA bases at the oxygen K-edge which occurs before Auger decay of the oxygen. Our approach is based on real-time time dependent density functional theory (RT-TDDFT). It is shown that the pronounced hole fluctuation observed around bonds of the initial core-hole results in various valence orbital migrations. Also, the same photo-core-ionized dynamics is studied for the related base pairs. We investigate the role of base pairing and H-bonding interactions in the attosecond CM dynamics. In particular, the creation of a core-hole in the oxygen involved in H-bonding leads to an enhancement of charge migration relative to the respective single bases. Importantly, the hole oscillation of the adenine-thymine base pair upon creation of a core-hole at the oxygen, which does not contribute to the donor-acceptor interactions (not H-bonded), decreases compared to the single thymine base. Understanding the detailed dynamics of the localized core-hole initiating CM process would open the way for chemically controlling DNA damage/repair in the future.
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Affiliation(s)
- Fatemeh Khalili
- Department of Physics, Shahid Beheshti University, Velenjak, Tehran 19839, Iran.
| | - Mohsen Vafaee
- Department of Chemistry, Tarbiat Modares University, P. O. Box 14115-175, Tehran, Iran.
| | - Babak Shokri
- Department of Physics, Shahid Beheshti University, Velenjak, Tehran 19839, Iran. .,Laser-Plasma Research Institute, Shahid Beheshti University, Velenjak, Tehran 19839, Iran
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Balanikas E, Banyasz A, Baldacchino G, Markovitsi D. Deprotonation Dynamics of Guanine Radical Cations †. Photochem Photobiol 2021; 98:523-531. [PMID: 34653259 DOI: 10.1111/php.13540] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/08/2021] [Indexed: 01/25/2023]
Abstract
This review is dedicated to guanine radical cations (G+ )· that are precursors to oxidatively generated damage to DNA. (G+ )· are unstable in neutral aqueous solution and tend to lose a proton. The deprotonation process has been studied by time-resolved absorption experiments in which (G+ )· radicals are produced either by an electron abstraction reaction, using an external oxidant, or by low-energy/low-intensity photoionization of DNA. Both the position of the released proton and the dynamics of the process depend on the secondary DNA structure. While deprotonation in duplex DNA leads to (G-H1)· radicals, in guanine quadruplexes the (G-H2)· analogs are observed. Deprotonation in monomeric guanosine proceeds with a time constant of ˜60 ns; in genomic DNA, it is completed within 2 µs; and in guanine quadruplexes, it spans from at least 30 ns to over 50 µs. Such a deprotonation dynamics in four-stranded structures, extended over more than three decades of times, is correlated with the anisotropic structure of DNA and the mobility of its hydration shell. In this case, commonly used second-order reaction models are inappropriate for its description.
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Affiliation(s)
| | - Akos Banyasz
- Université Paris-Saclay, CEA, CNRS, LIDYL, Gif-sur-Yvette, F-91191, France.,Univ Lyon, ENS de Lyon, CNRS, UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, Lyon, F-69342, France
| | - Gérard Baldacchino
- Université Paris-Saclay, CEA, CNRS, LIDYL, Gif-sur-Yvette, F-91191, France
| | - Dimitra Markovitsi
- Université Paris-Saclay, CEA, CNRS, LIDYL, Gif-sur-Yvette, F-91191, France
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The Two Faces of the Guanyl Radical: Molecular Context and Behavior. Molecules 2021; 26:molecules26123511. [PMID: 34207639 PMCID: PMC8227002 DOI: 10.3390/molecules26123511] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/29/2021] [Accepted: 06/01/2021] [Indexed: 12/16/2022] Open
Abstract
The guanyl radical or neutral guanine radical G(-H)• results from the loss of a hydrogen atom (H•) or an electron/proton (e–/H+) couple from the guanine structures (G). The guanyl radical exists in two tautomeric forms. As the modes of formation of the two tautomers, their relationship and reactivity at the nucleoside level are subjects of intense research and are discussed in a holistic manner, including time-resolved spectroscopies, product studies, and relevant theoretical calculations. Particular attention is given to the one-electron oxidation of the GC pair and the complex mechanism of the deprotonation vs. hydration step of GC•+ pair. The role of the two G(-H)• tautomers in single- and double-stranded oligonucleotides and the G-quadruplex, the supramolecular arrangement that attracts interest for its biological consequences, are considered. The importance of biomarkers of guanine DNA damage is also addressed.
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Bull GD, Thompson KC. The oxidation of guanine by photoionized 2-aminopurine. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY 2021. [DOI: 10.1016/j.jpap.2021.100025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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9
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Bell M, Kumar A, Sevilla MD. Electron-Induced Repair of 2'-Deoxyribose Sugar Radicals in DNA: A Density Functional Theory (DFT) Study. Int J Mol Sci 2021; 22:ijms22041736. [PMID: 33572317 PMCID: PMC7916153 DOI: 10.3390/ijms22041736] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/01/2021] [Accepted: 02/05/2021] [Indexed: 12/19/2022] Open
Abstract
In this work, we used ωB97XD density functional and 6-31++G** basis set to study the structure, electron affinity, populations via Boltzmann distribution, and one-electron reduction potentials (E°) of 2′-deoxyribose sugar radicals in aqueous phase by considering 2′-deoxyguanosine and 2′-deoxythymidine as a model of DNA. The calculation predicted the relative stability of sugar radicals in the order C4′• > C1′• > C5′• > C3′• > C2′•. The Boltzmann distribution populations based on the relative stability of the sugar radicals were not those found for ionizing radiation or OH-radical attack and are good evidence the kinetic mechanisms of the processes drive the products formed. The adiabatic electron affinities of these sugar radicals were in the range 2.6–3.3 eV which is higher than the canonical DNA bases. The sugar radicals reduction potentials (E°) without protonation (−1.8 to −1.2 V) were also significantly higher than the bases. Thus the sugar radicals will be far more readily reduced by solvated electrons than the DNA bases. In the aqueous phase, these one-electron reduced sugar radicals (anions) are protonated from solvent and thus are efficiently repaired via the “electron-induced proton transfer mechanism”. The calculation shows that, in comparison to efficient repair of sugar radicals by the electron-induced proton transfer mechanism, the repair of the cyclopurine lesion, 5′,8-cyclo-2′-dG, would involve a substantial barrier.
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Balanikas E, Banyasz A, Douki T, Baldacchino G, Markovitsi D. Guanine Radicals Induced in DNA by Low-Energy Photoionization. Acc Chem Res 2020; 53:1511-1519. [PMID: 32786340 DOI: 10.1021/acs.accounts.0c00245] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Guanine (G) radicals are precursors to DNA oxidative damage, correlated with carcinogenesis and aging. During the past few years, we demonstrated clearly an intriguing effect: G radicals can be generated upon direct absorption of UV radiation with energy significantly lower than the G ionization potential. Using nanosecond transient absorption spectroscopy, we studied the primary species, ejected electrons and guanine radicals, which result from photoionization of various DNA systems in aqueous solution.The DNA propensity to undergo electron detachment at low photon energies greatly depends on its secondary structure. Undetected for monomers or unstacked oligomers, this propensity may be 1 order of magnitude higher for G-quadruplexes than for duplexes. The experimental results suggest nonvertical processes, associated with the relaxation of electronic excited states. Theoretical studies are required to validate the mechanism and determine the factors that come into play. Such a mechanism, which may be operative over a broad excitation wavelength range, explains the occurrence of oxidative damage observed upon UVB and UVA irradiation.Quantification of G radical populations and their time evolution questions some widespread views. It appears that G radicals may be generated with the same probability as pyrimidine dimers, which are considered to be the major lesions induced upon absorption of low-energy UV radiation by DNA. As most radical cations undergo deprotonation, the vast majority of the final reaction products is expected to stem from long-lived deprotonated radicals. Consequently, when G radical cations are involved, the widely used oxidation marker 8-oxodG is not representative of the oxidative damage.Beyond the biological consequences, photogeneration of electron holes in G-quadruplexes may inspire applications in nanoelectronics; although four-stranded structures are currently studied as molecular wires, their behavior as photoconductors has not been explored so far.In the present Account, after highlighting some key experimental issues, we first describe the photoionization process, and then, we focus on radicals. We use as show-cases new results obtained for genomic DNA and Oxytricha G-quadruplexes. Generation and reaction dynamics of G radicals in these systems provide a representative picture of the phenomena reported previously for duplexes and G-quadruplexes, respectively.
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Affiliation(s)
| | - Akos Banyasz
- Univ Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F-69342 Lyon, France
| | - Thierry Douki
- Univ. Grenoble Alpes, CEA, CNRS, IRIG, SyMMES, F-38000 Grenoble France
| | - Gérard Baldacchino
- Université Paris-Saclay, CEA, CNRS, LIDYL, F-91191 Gif-sur-Yvette, France
| | - Dimitra Markovitsi
- Université Paris-Saclay, CEA, CNRS, LIDYL, F-91191 Gif-sur-Yvette, France
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Zheng L, Dai X, Su H, Greenberg MM. Independent Generation and Time-Resolved Detection of 2'-Deoxyguanosin-N2-yl Radicals. Angew Chem Int Ed Engl 2020; 59:13406-13413. [PMID: 32365264 PMCID: PMC7395871 DOI: 10.1002/anie.202005300] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 05/01/2020] [Indexed: 12/25/2022]
Abstract
Guanine radicals are important reactive intermediates in DNA damage. Hydroxyl radical (HO. ) has long been believed to react with 2'-deoxyguanosine (dG) generating 2'-deoxyguanosin-N1-yl radical (dG(N1-H). ) via addition to the nucleobase π-system and subsequent dehydration. This basic tenet was challenged by an alternative mechanism, in which the major reaction of HO. with dG was proposed to involve hydrogen atom abstraction from the N2-amine. The 2'-deoxyguanosin-N2-yl radical (dG(N2-H). ) formed was proposed to rapidly tautomerize to dG(N1-H). . We report the first independent generation of dG(N2-H). in high yield via photolysis of 1. dG(N2-H). is directly observed upon nanosecond laser flash photolysis (LFP) of 1. The absorption spectrum of dG(N2-H). is corroborated by DFT studies, and anti- and syn-dG(N2-H). are resolved for the first time. The LFP experiments showed no evidence for tautomerization of dG(N2-H). to dG(N1-H). within hundreds of microseconds. This observation suggests that the generation of dG(N1-H). via dG(N2-H). following hydrogen atom abstraction from dG is unlikely to be a major pathway when HO. reacts with dG.
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Affiliation(s)
- Liwei Zheng
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, 21218, USA
| | - Xiaojuan Dai
- Department of Chemistry, Beijing Normal University, Beijing, 100875, P. R. China
| | - Hongmei Su
- Department of Chemistry, Beijing Normal University, Beijing, 100875, P. R. China
| | - Marc M Greenberg
- Department of Chemistry, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD, 21218, USA
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12
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Zheng L, Dai X, Su H, Greenberg MM. Independent Generation and Time‐Resolved Detection of 2′‐Deoxyguanosin‐
N2
‐yl Radicals. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202005300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Liwei Zheng
- Department of Chemistry Johns Hopkins University 3400 N. Charles Street Baltimore MD 21218 USA
| | - Xiaojuan Dai
- Department of Chemistry Beijing Normal University Beijing 100875 P. R. China
| | - Hongmei Su
- Department of Chemistry Beijing Normal University Beijing 100875 P. R. China
| | - Marc M. Greenberg
- Department of Chemistry Johns Hopkins University 3400 N. Charles Street Baltimore MD 21218 USA
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13
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Dou Y, Wang Y, Duan Y, Liu B, Hu Q, Shen W, Sun H, Zhu Q. Color‐Tunable Light‐up Bioorthogonal Probes for In Vivo Two‐Photon Fluorescence Imaging. Chemistry 2020; 26:4576-4582. [DOI: 10.1002/chem.201905183] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/30/2019] [Indexed: 01/17/2023]
Affiliation(s)
- Yandong Dou
- College of Biotechnology and BioengineeringZhejiang University of Technology Hangzhou 310014 P. R. China
| | - Yajun Wang
- College of Biotechnology and BioengineeringZhejiang University of Technology Hangzhou 310014 P. R. China
| | - Yukun Duan
- Department of Chemical and Biomolecular EngineeringNational University of Singapore 4 Science Drive 4 117585 Singapore Singapore
| | - Bin Liu
- Department of Chemical and Biomolecular EngineeringNational University of Singapore 4 Science Drive 4 117585 Singapore Singapore
| | - Qinglian Hu
- College of Biotechnology and BioengineeringZhejiang University of Technology Hangzhou 310014 P. R. China
| | - Wei Shen
- Department of General SurgeryJinhua Municipal Central Hospital Jinhua 321000 P. R. China
| | - Hongyan Sun
- Department of ChemistryCity University of Hong Kong 83 Tat Chee Avenue, Kowloon Hong Kong P. R. China
| | - Qing Zhu
- College of Biotechnology and BioengineeringZhejiang University of Technology Hangzhou 310014 P. R. China
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14
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Kumar A, Adhikary A, Sevilla MD, Close DM. One-electron oxidation of ds(5'-GGG-3') and ds(5'-G(8OG)G-3') and the nature of hole distribution: a density functional theory (DFT) study. Phys Chem Chem Phys 2020; 22:5078-5089. [PMID: 32073006 PMCID: PMC7058519 DOI: 10.1039/c9cp06244k] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Of particular interest in radiation-induced charge transfer processes in DNA is the extent of hole localization immediately after ionization and subsequent relaxation. To address this, we considered double stranded oligomers containing guanine (G) and 8-oxoguanine (8OG), i.e., ds(5'-GGG-3') and ds(5'-G8OGG-3') in B-DNA conformation. Using DFT, we calculated a variety of properties, viz., vertical and adiabatic ionization potentials, spin density distributions in oxidized stacks, solvent and solute reorganization energies and one-electron oxidation potential (E0) in the aqueous phase. Calculations for the vertical state of the -GGG- cation radical showed that the spin was found mainly (67%) on the middle G. However, upon relaxation to the adiabatic -GGG- cation radical, the spin localized (96%) on the 5'-G, as observed in experiments. Hole localizations on the middle G and 3'-G were higher in energy by 0.5 kcal mol-1 and 0.4 kcal mol-1, respectively, than that of 5'-G. In the -G8OGG- cation radical, the spin localized only on the 8OG in both vertical and adiabatic states. The calculated vertical ionization potentials of -GGG- and -G8OGG- stacks were found to be lower than that of the vertical ionization potential of a single G in DNA. The calculated E0 values of -GGG- and -G8OGG- stacks are 1.15 and 0.90 V, respectively, which owing to stacking effects are substantially lower than the corresponding experimental E0 values of their monomers (1.49 and 1.18 V, respectively). SOMO to HOMO level switching is observed in these oxidized stacks. Consequently, our calculations predict that local double oxidations in DNA will form triplet diradical states, which are especially significant for high LET radiations.
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Affiliation(s)
- Anil Kumar
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, USA.
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15
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Balanikas E, Banyasz A, Baldacchino G, Markovitsi D. Populations and Dynamics of Guanine Radicals in DNA strands-Direct versus Indirect Generation. Molecules 2019; 24:molecules24132347. [PMID: 31247883 PMCID: PMC6651618 DOI: 10.3390/molecules24132347] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 06/14/2019] [Accepted: 06/18/2019] [Indexed: 01/17/2023] Open
Abstract
Guanine radicals, known to be involved in the damage of the genetic code and aging, are studied by nanosecond transient absorption spectroscopy. They are generated in single, double and four-stranded structures (G-quadruplexes) by one and two-photon ionization at 266 nm, corresponding to a photon energy lower than the ionization potential of nucleobases. The quantum yield of the one-photon process determined for telomeric G-quadruplexes (TEL25/Na+) is (5.2 ± 0.3) × 10−3, significantly higher than that found for duplexes containing in their structure GGG and GG sequences, (2.1 ± 0.4) × 10−3. The radical population is quantified in respect of the ejected electrons. Deprotonation of radical cations gives rise to (G-H1)• and (G-H2)• radicals for duplexes and G-quadruplexes, respectively. The lifetimes of deprotonated radicals determined for a given secondary structure strongly depend on the base sequence. The multiscale non-exponential dynamics of these radicals are discussed in terms of inhomogeneity of the reaction space and continuous conformational motions. The deviation from classical kinetic models developed for homogeneous reaction conditions could also be one reason for discrepancies between the results obtained by photoionization and indirect oxidation, involving a bi-molecular reaction between an oxidant and the nucleic acid.
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Affiliation(s)
| | - Akos Banyasz
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
- Univ Lyon, ENS de Lyon, CNRS UMR 5182, Université Claude Bernard Lyon 1, Laboratoire de Chimie, F-69342 Lyon, France.
| | - Gérard Baldacchino
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
| | - Dimitra Markovitsi
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
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Banyasz A, Balanikas E, Martinez-Fernandez L, Baldacchino G, Douki T, Improta R, Markovitsi D. Radicals Generated in Tetramolecular Guanine Quadruplexes by Photoionization: Spectral and Dynamical Features. J Phys Chem B 2019; 123:4950-4957. [PMID: 31117607 DOI: 10.1021/acs.jpcb.9b02637] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
G-quadruplexes are four-stranded DNA structures playing a key role in many biological functions and are promising for applications in the field of nanoelectronics. Characterizing the generation and fate of radical cations (electron holes) within these systems is important in relation to the DNA oxidative damage and/or conductivity issues. This study focuses on guanine radicals in G-quadruplexes formed by association of four TGGGGT strands in the presence of Na+ cations, (TG4T)4/Na+. Using nanosecond transient spectroscopy with 266 nm excitation, we quantitatively characterize hydrated ejected electrons and three types of guanine radicals. We show that, at an energy lower by 2.7 eV than the guanine ionization potential, one-photon ionization occurs with quantum yield of (3.5 ± 0.5) × 10-3. Deprotonation of the radical cations is completed within 20 μs, leading to the formation of (G-H2)• radicals, following a strongly nonexponential decay pattern. Within 10 ms, the latter undergoes tautomerization to deprotonated (G-H1)• radicals. The dynamics of the various radicals determined for (TG4T)4/Na+, in connection to those reported previously for telomeric G-quadruplexes TEL21/Na+, is correlated with energetic factors computed by quantum chemical methods. The faster deprotonation of radical cations in (TG4T)4/Na+ compared to TEL21/Na+ explains that irradiation of the former does not generate 8-oxodGuo, which is readily detected by high-performance liquid chromatography/mass spectrometry in the case of TEL21/Na+.
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Affiliation(s)
- Akos Banyasz
- LIDYL, CEA, CNRS, Université Paris-Saclay , F-91191 Gif-sur-Yvette , France.,Univ Lyon, ENS de Lyon, CNRS UMR 5182 , Université Claude Bernard Lyon 1, Laboratoire de Chimie , F-69342 Lyon , France
| | | | - Lara Martinez-Fernandez
- LIDYL, CEA, CNRS, Université Paris-Saclay , F-91191 Gif-sur-Yvette , France.,Departamento de Química , Universidad Autónoma de Madrid , c/ Francisco Tomás y Valiente 7, Cantoblanco , 28049 Madrid , Spain
| | - Gérard Baldacchino
- LIDYL, CEA, CNRS, Université Paris-Saclay , F-91191 Gif-sur-Yvette , France
| | - Thierry Douki
- Univ. Grenoble-Alpes, CEA, CNRS, SyMMES UMR , 5819 Grenoble , France
| | - Roberto Improta
- LIDYL, CEA, CNRS, Université Paris-Saclay , F-91191 Gif-sur-Yvette , France.,Istituto Biostrutture e Bioimmagini-Consiglio Nazionale delle Ricerche , Via Mezzocannone 16 , I-80134 Napoli , Italy
| | - Dimitra Markovitsi
- LIDYL, CEA, CNRS, Université Paris-Saclay , F-91191 Gif-sur-Yvette , France
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