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Markovitsi D. On the Use of the Intrinsic DNA Fluorescence for Monitoring Its Damage: A Contribution from Fundamental Studies. ACS OMEGA 2024; 9:26826-26837. [PMID: 38947837 PMCID: PMC11209687 DOI: 10.1021/acsomega.4c02256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/07/2024] [Revised: 05/02/2024] [Accepted: 05/08/2024] [Indexed: 07/02/2024]
Abstract
The assessment of DNA damage by means of appropriate fluorescent probes is widely spread. In the specific case of UV-induced damage, it has been suggested to use the emission of dimeric photoproducts as an internal indicator for the efficacy of spermicidal lamps. However, in the light of fundamental studies on the UV-induced processes, outlined in this review, this is not straightforward. It is by now well established that, in addition to photodimers formed via an electronic excited state, photoionization also takes place with comparable or higher quantum yields, depending on the irradiation wavelength. Among the multitude of final lesions, some have been fully characterized, but others remain unknown; some of them may emit, while others go undetected upon monitoring fluorescence, the result being strongly dependent on both the irradiation and the excitation wavelength. In contrast, the fluorescence of undamaged nucleobases associated with emission from ππ* states, localized or excitonic, appearing at wavelengths shorter than 330 nm is worthy of being explored to this end. Despite its low quantum yield, it is readily detected nowadays. Its intensity decreases due to the disappearance of the reacting nucleobases and the loss of exciton coherence provoked by the presence of lesions, independently of their type. Thus, it could potentially provide valuable information about the DNA damage induced, not only by UV radiation but also by other sanitizing or therapeutic agents.
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Affiliation(s)
- Dimitra Markovitsi
- Université Paris-Saclay, CNRS,
Institut de Chimie Physique, UMR8000, 91405 Orsay, France
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2
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Cataldo PG, Iramain MA, Castillo MV, Manzur ME, Romano E, Brandán SA. Vibrational assignments of cyclic dimers and inter-monomers of adenine relating FT-IR, FT-Raman and UV spectra with SQMFF and DFT calculations. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2024; 306:123540. [PMID: 37898058 DOI: 10.1016/j.saa.2023.123540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 10/13/2023] [Accepted: 10/14/2023] [Indexed: 10/30/2023]
Abstract
In this work, three different cyclic dimers and a tetramer of adenine taken from the experimental structure determined by X-ray diffraction have been studied by combination of experimental FT-IR, FT-Raman and UV-Visible spectra with hybrid B3LYP/6-311++G** and scaled quantum mechanical force field (SQMFF) calculations in order to perform the complete assignments of bands observed in the vibrational spectra. The characteristics of different N-H···N interactions of those three cyclic structures together with the group of IR bands observed between 2865 and 2599 cm-1 have been elucidated considering the tetrameric structure. The cyclic dimers and the tetramer of adenine confirm that the bands observed between 2865 and 2599 cm-1 are not due to N-H···N interactions but to bands of combination, as was previously suggested. The experimental available deuterated IR and terahertz spectra have allowed the complete assignments of regions of higher and lower wavenumbers. Good correlations were acquired comparing the theoretical IR, Raman and UV spectra of three species and the tetramer with the analogous experimental ones, suggesting the presence of all species in both phases. Vibronic bands are observed in the electronic spectra when adenine concentration is increased in aqueous solution evidencing the presence of monomer, tautomers and dimers, as reported by different studies. Similar characteristics of H bonds interactions are predicted for dimers 1 and 2 but different from the dimer 3, as revealed by using NBO and AIM calculations. Different scaled force constants values were found for the cyclic dimers 1 and 2, as compared to the corresponding to dimer 3.
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Affiliation(s)
- Pablo G Cataldo
- Cátedra de Química General, Instituto de Química Inorgánica, Facultad de Bioquímica. Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471, (4000) San Miguel de Tucumán, Tucumán, Argentina
| | - Maximiliano A Iramain
- Cátedra de Química General, Instituto de Química Inorgánica, Facultad de Bioquímica. Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471, (4000) San Miguel de Tucumán, Tucumán, Argentina
| | - María V Castillo
- Cátedra de Química General, Instituto de Química Inorgánica, Facultad de Bioquímica. Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471, (4000) San Miguel de Tucumán, Tucumán, Argentina
| | - María E Manzur
- Cátedra de Química General, Instituto de Química Inorgánica, Facultad de Bioquímica. Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471, (4000) San Miguel de Tucumán, Tucumán, Argentina
| | - Elida Romano
- Cátedra de Química General, Instituto de Química Inorgánica, Facultad de Bioquímica. Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471, (4000) San Miguel de Tucumán, Tucumán, Argentina
| | - Silvia Antonia Brandán
- Cátedra de Química General, Instituto de Química Inorgánica, Facultad de Bioquímica. Química y Farmacia, Universidad Nacional de Tucumán, Ayacucho 471, (4000) San Miguel de Tucumán, Tucumán, Argentina.
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3
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Ventura B, Veclani D, Venturini A, Armaroli N, Baroncini M, Ceroni P, Marchini M. Elucidating the Excited State Behavior of Pyridyl Pyridinium Systems via Computational and Transient Absorption Studies of Tetrahedral Multichromophoric Arrays and their Model Compounds. Chemistry 2023; 29:e202301853. [PMID: 37563909 DOI: 10.1002/chem.202301853] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Revised: 08/09/2023] [Accepted: 08/10/2023] [Indexed: 08/12/2023]
Abstract
The tetrahedral shape-persistent molecule 14+ , containing four identical pyridyl pyridinium units connected via a sp3 hybridized carbon atom, has been investigated in detail by means of steady-state and time resolved spectroscopy. Remarkable photophysical properties are observed, particularly in comparison with protonated and methylated analogues (1H4 8+ , 1Me4 8+ ), which exhibit substantially shorter excited state lifetimes and lower emission quantum yields. Theoretical studies have rationalized the behavior of the tetrameric molecules relative to the monomers, with DFT and TD-DFT calculations corroborating steady-state (absorption and emission) and transient absorption spectra. The behavior of the monomeric compounds (each consisting in one of the four identical subunits of the tetramers, i. e., 2+ , 2H2+ and 2Me2+ ) considerably differs from that of the tetramers, indicating a strong electronic interaction between the subunits in the tetrameric species, likely promoted by the homoconjugation through the connecting sp3 C atom. 2+ is characterized by a peculiar S1 -S2 excited state inversion, whereas the short-lived emitting S1 state of 2H2+ and 2Me2+ exhibits a partial charge-transfer character, as substantiated by spectro-electrochemical studies. Among the six investigated systems, only 14+ is a sizeable luminophore (Φem =0.15), which is related to the peculiar features of its singlet state.
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Affiliation(s)
- Barbara Ventura
- Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche (ISOF-CNR), Via P. Gobetti 101, 40129, Bologna, Italy
| | - Daniele Veclani
- Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche (ISOF-CNR), Via P. Gobetti 101, 40129, Bologna, Italy
| | - Alessandro Venturini
- Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche (ISOF-CNR), Via P. Gobetti 101, 40129, Bologna, Italy
| | - Nicola Armaroli
- Istituto per la Sintesi Organica e la Fotoreattività, Consiglio Nazionale delle Ricerche (ISOF-CNR), Via P. Gobetti 101, 40129, Bologna, Italy
| | - Massimo Baroncini
- CLAN-Center for Light Activated Nanostructures, Consiglio Nazionale delle Ricerche (ISOF-CNR), Via P. Gobetti 101, 40129, Bologna, Italy
- Dipartimento di Scienze e Tecnologie Agro-alimentari, Università di Bologna, Viale G. Fanin 50, 40127, Bologna, Italy
| | - Paola Ceroni
- Dipartimento di Chimica "G. Ciamician", Università di Bologna, Via F. Selmi 2, 40126, Bologna, Italy
| | - Marianna Marchini
- Dipartimento di Chimica "G. Ciamician", Università di Bologna, Via F. Selmi 2, 40126, Bologna, Italy
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Balanikas E, Gustavsson T, Markovitsi D. Fluorescence of Bimolecular Guanine Quadruplexes: From Femtoseconds to Nanoseconds. J Phys Chem B 2023; 127:172-179. [PMID: 36577031 DOI: 10.1021/acs.jpcb.2c07647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The paper deals with the fluorescence of guanine quadruplexes (G4) formed by association of two DNA strands d(GGGGTTTTGGGG) in the presence of K+ cations, noted as OXY/K+ in reference to the protozoon Oxytricha nova, whose telomere contains TTTTGGGG repeats. They were studied by steady-state and time-resolved techniques, time-correlated single photon counting, and fluorescence upconversion. The maximum of the OXY/K+ fluorescence spectrum is located at 334 nm, and the quantum yield is 5.8 × 10-4. About 75% of the photons are emitted before 100 ps and stem from ππ* states, possibly with a small contribution of charge transfer. Time-resolved fluorescence anisotropy measurements indicate that ultrafast (<330 fs) excitation transfer, due to internal conversion among exciton states, is more efficient in OXY/K+ compared to previously studied G4 structures. This is attributed to the arrangement of the peripheral thymines in two diagonal loops with restricted mobility, facilitating the interaction among them and with guanines. Thymines should also be responsible for a weak intensity excimer/exciplex emission band, peaking at 445 nm. Finally, the longest living fluorescence component (∼2.1 ns) is observed at the blue side of the spectrum. So far, high-energy long-lived emitting states had been reported only for double-stranded structures but not for G4.
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Affiliation(s)
| | - Thomas Gustavsson
- CEA, CNRS, LIDYL, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | - Dimitra Markovitsi
- CEA, CNRS, LIDYL, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.,CNRS, Institut de Chimie Physique, UMR8000, Université Paris-Saclay, 91405 Orsay, France
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5
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Martínez Fernández L, Santoro F, Improta R. Nucleic Acids as a Playground for the Computational Study of the Photophysics and Photochemistry of Multichromophore Assemblies. Acc Chem Res 2022; 55:2077-2087. [PMID: 35833758 DOI: 10.1021/acs.accounts.2c00256] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
ConspectusThe interaction between light and multichromophoric assemblies (MCAs) is the primary event of many fundamental processes, from photosynthesis to organic photovoltaics, and it triggers dynamical processes that share remarkable similarities at the molecular scale: light absorption, energy and charge transfer, internal conversions, emission, and so on. Those events often involve many chromophores and different excited electronic states that are coupled on an ultrafast time scale. This Account aims to discuss some of the chemical physical effects ruling these processes, a fundamental step toward their control, based on our experience on nucleic acids.In the last 15 years, we have, indeed, studied the photophysics and photochemistry of DNA and its components. By combining different quantum mechanical methods, we investigated the molecular processes responsible for the damage of the genetic code or, on the contrary, those preventing it by dissipating the excess energy deposited in the system by UV absorption. Independently of its fundamental biological role, DNA, with its fluctuating closely stacked bases stabilized by weak nonbonding interactions, can be considered a prototypical MCA. Therefore, it allows one to tackle within a single system many of the conceptual and methodological challenges involved in the study of photoinduced processes in MCA.In this Account, by using the outcome of our studies on oligonucleotides as a guideline, we thus highlight the most critical modellistic issues to be faced when studying, either experimentally or computationally, the interaction between UV light and DNA and, at the same time, bring out their general relevance for the study of MCAs.We first discuss the rich photoactivated dynamics of nucleobases (the chromophores), highlighting the main effects modulating the interplay between their excited states and how the latter can affect the photoactivated dynamics of the polynucleotides, either providing effective monomer-like nonradiative decay routes or triggering reactive processes (e.g., triplet generation).We then tackle the reaction paths involving multiple bases, showing that in the DNA duplex the most important ones involve two stacked bases, forming a neutral excimer or a charge transfer (CT) state, which exhibit different spectral signatures and photochemical reactivity. In particular, we analyze the factors affecting the dynamic equilibrium between the excimer and CT, such as the fluctuations of the backbone or the rearrangement of the solvent.Next, we highlight the importance of the effects not directly connected to the chromophores, such as the flexibility of the backbone or the solvent effect. The former, affecting the stacking geometry of the bases, can determine the preference between different deactivation paths. The latter is particularly influential for CT states, making very important an accurate treatment of dynamical solvation effects, involving both the solvent bulk and specific solute-solvent interactions.In the last section, we describe the main methodological challenges related to the study of polynucleotide excited states and stress the benefits derived by the integration of complementary approaches, both computational and experimental. Only exploiting different point of views, in our opinion, it is possible to shed light on the complex phenomena triggered by light absorption in DNA, as in every MCA.
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Affiliation(s)
- Lara Martínez Fernández
- Departamento de Química, Facultad de Ciencias and Institute for Advanced Research in Chemistry (IADCHEM), Universidad Autónoma de Madrid, Campus de Excelencia UAM-CSIC, 28049 Madrid, Spain
| | - Fabrizio Santoro
- Istituto di Chimica dei Composti Organometallici (ICCOM-CNR), Area della Ricerca del CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Roberto Improta
- Istituto di Biostrutture e Bioimmagini-CNR (IBB-CNR), Via De Amicis 95, I-80145 Napoli, Italy
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6
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Balanikas E, Martinez-Fernandez L, Baldacchino G, Markovitsi D. Electron Holes in G-Quadruplexes: The Role of Adenine Ending Groups. Int J Mol Sci 2021; 22:ijms222413436. [PMID: 34948235 PMCID: PMC8704496 DOI: 10.3390/ijms222413436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 11/30/2021] [Accepted: 12/01/2021] [Indexed: 11/16/2022] Open
Abstract
The study deals with four-stranded DNA structures (G-Quadruplexes), known to undergo ionization upon direct absorption of low-energy UV photons. Combining quantum chemistry calculations and time-resolved absorption spectroscopy with 266 nm excitation, it focuses on the electron holes generated in tetramolecular systems with adenine groups at the ends. Our computations show that the electron hole is placed in a single guanine site, whose location depends on the position of the adenines at the 3' or 5' ends. This position also affects significantly the electronic absorption spectrum of (G+)● radical cations. Their decay is highly anisotropic, composed of a fast process (<2 µs), followed by a slower one occurring in ~20 µs. On the one hand, they undergo deprotonation to (G-H2)● radicals and, on the other, they give rise to a reaction product absorbing in the 300-500 nm spectral domain.
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Affiliation(s)
- Evangelos Balanikas
- LIDYL, CEA, CNRS, Université Paris-Saclay, 91191 Gif-sur-Yvette, France; (E.B.); (G.B.)
| | - Lara Martinez-Fernandez
- Departamento de Química, Modúlo 13, Facultad de Ciencias and IADCHEM (Institute for Advanced Research in Chemistry), Campus de Excelencia UAM-CSIC, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain
- Correspondence: (L.M.-F.); or (D.M.)
| | - Gérard Baldacchino
- LIDYL, CEA, CNRS, Université Paris-Saclay, 91191 Gif-sur-Yvette, France; (E.B.); (G.B.)
| | - Dimitra Markovitsi
- LIDYL, CEA, CNRS, Université Paris-Saclay, 91191 Gif-sur-Yvette, France; (E.B.); (G.B.)
- Correspondence: (L.M.-F.); or (D.M.)
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7
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Xu Y, Yang M, Ma Q, Di X, Wu G. A bio-inspired fluorescent nano-injectable hydrogel as a synergistic drug delivery system. NEW J CHEM 2021. [DOI: 10.1039/d0nj05719c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
A nano-injectable hydrogel with fluorescence properties and controlled sequential release of dual drugs.
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Affiliation(s)
- Yue Xu
- Key Laboratory of Functional Polymer Materials
- Institute of Polymer Chemistry
- College of Chemistry
- Nankai University
- Tianjin 300071
| | - Mingming Yang
- Key Laboratory of Functional Polymer Materials
- Institute of Polymer Chemistry
- College of Chemistry
- Nankai University
- Tianjin 300071
| | - Qiyue Ma
- Key Laboratory of Functional Polymer Materials
- Institute of Polymer Chemistry
- College of Chemistry
- Nankai University
- Tianjin 300071
| | - Xiang Di
- Key Laboratory of Functional Polymer Materials
- Institute of Polymer Chemistry
- College of Chemistry
- Nankai University
- Tianjin 300071
| | - Guolin Wu
- Key Laboratory of Functional Polymer Materials
- Institute of Polymer Chemistry
- College of Chemistry
- Nankai University
- Tianjin 300071
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8
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Balanikas E, Banyasz A, Baldacchino G, Markovitsi D. Guanine Radicals Generated in Telomeric G-Quadruplexes by Direct Absorption of Low-Energy UV Photons: Effect of Potassium Ions. Molecules 2020; 25:E2094. [PMID: 32365780 PMCID: PMC7248781 DOI: 10.3390/molecules25092094] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 04/23/2020] [Accepted: 04/27/2020] [Indexed: 11/16/2022] Open
Abstract
The study deals with the primary species, ejected electrons, and guanine radicals, leading to oxidative damage, that is generated in four-stranded DNA structures (guanine quadruplexes) following photo-ionization by low-energy UV radiation. Performed by nanosecond transient absorption spectroscopy with 266 nm excitation, it focusses on quadruplexes formed by folding of GGG(TTAGGG)3 single strands in the presence of K+ ions, TEL21/K+. The quantum yield for one-photon ionization (9.4 × 10-3) was found to be twice as high as that reported previously for TEL21/Na+. The overall population of guanine radicals decayed faster, their half times being, respectively, 1.4 and 6.7 ms. Deprotonation of radical cations extended over four orders of magnitude of time; the faster step, concerning 40% of their population, was completed within 500 ns. A reaction intermediate, issued from radicals, whose absorption spectrum peaked around 390 nm, was detected.
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Affiliation(s)
- Evangelos Balanikas
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France; (E.B.); (A.B.); (G.B.)
| | - Akos Banyasz
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France; (E.B.); (A.B.); (G.B.)
- 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; (E.B.); (A.B.); (G.B.)
| | - Dimitra Markovitsi
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France; (E.B.); (A.B.); (G.B.)
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Martinez-Fernandez L, Gustavsson T, Diederichsen U, Improta R. Excited State Dynamics of 8-Vinyldeoxyguanosine In Aqueous Solution Studied by Time-Resolved Fluorescence Spectroscopy and Quantum Mechanical Calculations. Molecules 2020; 25:E824. [PMID: 32070032 PMCID: PMC7071107 DOI: 10.3390/molecules25040824] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 02/10/2020] [Accepted: 02/10/2020] [Indexed: 02/08/2023] Open
Abstract
The fluorescent base guanine analog, 8-vinyl-deoxyguanosine (8vdG), is studied in solution using a combination of optical spectroscopies, notably femtosecond fluorescence upconversion and quantum chemical calculations, based on time-dependent density functional theory (TD-DFT) and including solvent effect by using a mixed discrete-continuum model. In all investigated solvents, the fluorescence is very long lived (3-4 ns), emanating from a stable excited state minimum with pronounced intramolecular charge-transfer character. The main non-radiative decay channel features a sizeable energy barrier and it is affected by the polarity and the H-bonding properties of the solvent. Calculations provide a picture of dynamical solvation effects fully consistent with the experimental results and show that the photophysical properties of 8vdG are modulated by the orientation of the vinyl group with respect to the purine ring, which in turn depends on the solvent. These findings may have importance for the understanding of the fluorescence properties of 8vdG when incorporated in a DNA helix.
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Affiliation(s)
- Lara Martinez-Fernandez
- Departamento de Química, Facultad de Ciencias and IADCHEM (Institute for Advanced Research in Chemistry) Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain;
| | - Thomas Gustavsson
- Université Paris-Saclay, CEA, CNRS, LIDYL, 91191 Gif-sur-Yvette, France
| | - Ulf Diederichsen
- Univ Goettingen, Inst Organ & Biomol Chem, Tammannstr 2, D-37077 Goettingen, Germany;
| | - Roberto Improta
- Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone 16, I-80134 Napoli, Italy
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Valadan M, Pomarico E, Della Ventura B, Gesuele F, Velotta R, Amoresano A, Pinto G, Chergui M, Improta R, Altucci C. A multi-scale time-resolved study of photoactivated dynamics in 5-benzyl uracil, a model for DNA/protein interactions. Phys Chem Chem Phys 2019; 21:26301-26310. [PMID: 31686060 DOI: 10.1039/c9cp03839f] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We combine fluorescence up-conversion and time correlated single photon counting experiments to investigate the 5-benzyl uracil excited state dynamics in methanol from 100 fs up to several ns. This molecule has been proposed as a model for DNA/protein interactions. Our results show emission bands at about 310 and 350 nm that exhibit bi-exponential sub-ps decays. Calculations, including solvent effects by a mixed discrete-continuum model, indicate that the Franck Condon region is characterized by significant coupling between the excited states of the benzyl and the uracil moieties, mirrored by the short-lived emission at 310 nm. Two main ground state recovery pathways are identified, both contributing to the 350 nm emission. The first 'photophysical' decay path involves a ππ* excited state localized on the uracil and is connected to the ground electronic state by an easily accessible crossing with S0, accounting for the short lifetime component. Simulations indicate that a possible second pathway is characterized by exciplex formation, with partial benzene → uracil charge transfer character, that may lead instead to photocyclization. The relevance of our results is discussed in view of the photoactivated dynamics of DNA/protein complexes, with implications on their interaction mechanisms.
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Affiliation(s)
- Mohammadhassan Valadan
- Department of Physics "Ettore Pancini", University of Naples "Federico II", Naples, 80126, Italy.
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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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12
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Banyasz A, Ketola T, Martínez-Fernández L, Improta R, Markovitsi D. Adenine radicals generated in alternating AT duplexes by direct absorption of low-energy UV radiation. Faraday Discuss 2019; 207:181-197. [PMID: 29372211 DOI: 10.1039/c7fd00179g] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
There is increasing evidence that the direct absorption of photons with energies that are lower than the ionization potential of nucleobases may result in oxidative damage to DNA. The present work, which combines nanosecond transient absorption spectroscopy and quantum mechanical calculations, studies this process in alternating adenine-thymine duplexes (AT)n. We show that the one-photon ionization quantum yield of (AT)10 at 266 nm (4.66 eV) is (1.5 ± 0.3) × 10-3. According to our PCM/TD-DFT calculations carried out on model duplexes composed of two base pairs, (AT)1 and (TA)1, simultaneous base pairing and stacking does not induce important changes in the absorption spectra of the adenine radical cation and deprotonated radical. The adenine radicals, thus identified in the time-resolved spectra, disappear with a lifetime of 2.5 ms, giving rise to a reaction product that absorbs at 350 nm. In parallel, the fingerprint of reaction intermediates other than radicals, formed directly from singlet excited states and assigned to AT/TA dimers, is detected at shorter wavelengths. PCM/TD-DFT calculations are carried out to map the pathways leading to such species and to characterize their absorption spectra; we find that, in addition to the path leading to the well-known TA* photoproduct, an AT photo-dimerization path may be operative in duplexes.
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Affiliation(s)
- Akos Banyasz
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France.
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13
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Abstract
Using as a model the single adenine strand (dA)20, we study the ultrafast evolution of electronic excitations in DNA with a time resolution of 30 fs. Our transient absorption spectra in the UV and visible spectral domains show that internal conversion among photogenerated exciton states occurs within 100 fs. Subsequently, the ππ* states acquire progressively charge-transfer character before being completely trapped, within 3 ps, by fully developed charge-transfer states corresponding to transfer of an electron from one adenine moiety to another (A+A-).
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Affiliation(s)
- Rocio Borrego-Varillas
- IFN-CNR, Dipartimento di Fisica , Politecnico di Milano , Piazza Leonardo da Vinci 32 , I-20133 Milano , Italy
| | - Giulio Cerullo
- IFN-CNR, Dipartimento di Fisica , Politecnico di Milano , Piazza Leonardo da Vinci 32 , I-20133 Milano , Italy
| | - Dimitra Markovitsi
- LIDYL, CEA, CNRS , Université Paris-Saclay , F-91191 Gif-sur-Yvette , France
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14
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Cadet J, Douki T. Formation of UV-induced DNA damage contributing to skin cancer development. Photochem Photobiol Sci 2018; 17:1816-1841. [PMID: 29405222 DOI: 10.1039/c7pp00395a] [Citation(s) in RCA: 216] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
UV-induced DNA damage plays a key role in the initiation phase of skin cancer. When left unrepaired or when damaged cells are not eliminated by apoptosis, DNA lesions express their mutagneic properties, leading to the activation of proto-oncogene or the inactivation of tumor suppression genes. The chemical nature and the amount of DNA damage strongly depend on the wavelength of the incident photons. The most energetic part of the solar spectrum at the Earth's surface (UVB, 280-320 nm) leads to the formation of cyclobutane pyrimidine dimers (CPDs) and pyrimidine (6-4) pyrimidone photoproducts (64PPs). Less energetic but 20-times more intense UVA (320-400 nm) also induces the formation of CPDs together with a wide variety of oxidatively generated lesions such as single strand breaks and oxidized bases. Among those, 8-oxo-7,8-dihydroguanine (8-oxoGua) is the most frequent since it can be produced by several mechanisms. Data available on the respective yield of DNA photoproducts in cells and skin show that exposure to sunlight mostly induces pyrimidine dimers, which explains the mutational signature found in skin tumors, with lower amounts of 8-oxoGua and strand breaks. The present review aims at describing the basic photochemistry of DNA and discussing the quantitative formation of the different UV-induced DNA lesions reported in the literature. Additional information on mutagenesis, repair and photoprotection is briefly provided.
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Affiliation(s)
- Jean Cadet
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine, 3001 12e Avenue Nord, Université de Sherbrooke, Sherbrooke, Québec JIH 5N4, Canada.
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15
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Martinez-Fernandez L, Prampolini G, Cerezo J, Liu Y, Santoro F, Improta R. Solvent effect on the energetics of proton coupled electron transfer in guanine-cytosine pair in chloroform by mixed explicit and implicit solvation models. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.07.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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16
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Martínez-Fernández L, Improta R. Sequence dependence on DNA photochemistry: a computational study of photodimerization pathways in TpdC and dCpT dinucleotides. Photochem Photobiol Sci 2018; 17:586-591. [PMID: 29624198 DOI: 10.1039/c8pp00040a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The excited states involved in the main photodimerization paths in TpdC and dCpT are mapped by PCM/TD-M052X calculations, considering different dinucleotide conformers. As for TT steps, a cyclobutane pyrimidine dimer (CPD) is formed on the PES of the lowest energy exciton, delocalized over two stacked pyrimidines; 6-4 pyrimidine-pyrimidone (64-PP) adduct's formation involves instead a 5'-ter → 3'-ter charge transfer state. For dCpT, 64-PP dimerization occurs via a two-step reaction, which proceeds through an oxetane intermediate. For TpdC, instead, the final 64-PP product is obtained in a single step and it is as stable as the CPD photoproduct, explaining the relatively large yield of 64-PP found experimentally for TC steps in DNA.
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Affiliation(s)
- Lara Martínez-Fernández
- Consiglio Nationale delle Ricerche, Istituto di Biostrutture e Bioimmagini, 80134 Naples, Italy. and LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | - Roberto Improta
- Consiglio Nationale delle Ricerche, Istituto di Biostrutture e Bioimmagini, 80134 Naples, Italy. and LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
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17
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Martínez-Fernández L, Improta R. Novel adenine/thymine photodimerization channels mapped by PCM/TD-DFT calculations on dApT and TpdA dinucleotides. Photochem Photobiol Sci 2018. [PMID: 28640303 DOI: 10.1039/c7pp00154a] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Despite the biological relevance of AT-rich DNA sequences, the excited state paths associated with the photochemical reactions involving adenine and thymine stacked pairs have never been characterized, and the structure of the most abundant photoproduct in DNA is unknown. PCM/TD-M052X calculations on dApT and TpdA unveil the paths leading to the main photoproduct in TpdA, provide new insights into the reasons why it is not formed in dApT and show the existence of a new photochemical path, which could produce the precursor of the most abundant genomic AT/TA photoproduct. Our calculations confirm that anti/anti conformers are photochemically active and show that the dynamical solvation effects could significantly modulate the reaction yields.
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Affiliation(s)
- Lara Martínez-Fernández
- Consiglio Nazionale delle Ricerche, Istituto di Biostrutture e Bioimmagini, 80134 Naples, Italy
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18
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Martinez-Fernandez L, Improta R. Photoactivated proton coupled electron transfer in DNA: insights from quantum mechanical calculations. Faraday Discuss 2018; 207:199-216. [DOI: 10.1039/c7fd00195a] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The energetics of the two main proton coupled electron transfer processes that could occur in DNA are determined by means of time dependent-DFT calculations, using the M052X functional and the polarizable continuum model to include solvent effect.
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Affiliation(s)
| | - Roberto Improta
- Consiglio Nazionale delle Ricerche
- Istituto di Biostrutture e Bioimmagini
- 80136 Naples
- Italy
- LIDYL
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19
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Conti I, Martínez-Fernández L, Esposito L, Hofinger S, Nenov A, Garavelli M, Improta R. Multiple Electronic and Structural Factors Control Cyclobutane Pyrimidine Dimer and 6-4 Thymine-Thymine Photodimerization in a DNA Duplex. Chemistry 2017; 23:15177-15188. [PMID: 28809462 DOI: 10.1002/chem.201703237] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Indexed: 11/09/2022]
Abstract
The T-T photodimerization paths leading to the formation of cyclobutane pyrimidine dimer (CPD) and 6-4 pyrimidine pyrimidone (64-PP), the two main DNA photolesions, have been resolved for a T-T step in a DNA duplex by two complementary state-of-the-art quantum mechanical approaches: QM(CASPT2//CASSCF)/MM and TD-DFT/PCM. Based on the analysis of several different representative structures, we define a new-ensemble of cooperating geometrical and electronic factors (besides the distance between the reacting bonds) ruling T-T photodimerization in DNA. CPD is formed by a barrierless path on an exciton state delocalized over the two bases. Large interbase stacking and shift values, together with a small pseudorotation phase angle for T at the 3'-end, favor this reaction. The oxetane intermediate, leading to a 64-PP adduct, is formed on a singlet T→T charge-transfer state and is favored by a large interbase angle and slide values. A small energy barrier (<0.3 eV) is associated to this path, likely contributing to the smaller quantum yield observed for this process. Eventually, a clear directionality is always shown by the electronic excitation characterizing the singlet photoactive state driving the photodimerization process: an exciton that is more localized on T3 and a 5'-T→3'-T charge transfer for CPD and oxetane formation, respectively, thus calling for specific electronic constraints.
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Affiliation(s)
- Irene Conti
- Dipartimento di Chimica Industriale "T. Montanari", Università di Bologna, Viale Risorgimento 4, 40136, Bologna, Italy
| | | | - Luciana Esposito
- Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone 16, 80134, Napoli, Italy
| | - Siegfried Hofinger
- TU Wien, Zentraler Informatikdienst, Wiedner Hauptstrasse 8-10, 1040, Wien, Austria.,Department of Physics, Michigan Technological University, 1400 Townsend Drive, Houghton, MI, 49331-1295, USA
| | - Artur Nenov
- Dipartimento di Chimica Industriale "T. Montanari", Università di Bologna, Viale Risorgimento 4, 40136, Bologna, Italy
| | - Marco Garavelli
- Dipartimento di Chimica Industriale "T. Montanari", Università di Bologna, Viale Risorgimento 4, 40136, Bologna, Italy
| | - Roberto Improta
- Istituto di Biostrutture e Bioimmagini, CNR, Via Mezzocannone 16, 80134, Napoli, Italy.,LIDYL, CEA, CNRS, Université Paris, Saclay, 91191, Gif-sur-Yvette, France
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20
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Wu X, Karsili TNV, Domcke W. Role of Electron-Driven Proton-Transfer Processes in the Ultrafast Deactivation of Photoexcited Anionic 8-oxoGuanine-Adenine and 8-oxoGuanine-Cytosine Base Pairs. Molecules 2017; 22:molecules22010135. [PMID: 28098833 PMCID: PMC6155867 DOI: 10.3390/molecules22010135] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 12/28/2016] [Accepted: 01/10/2017] [Indexed: 11/16/2022] Open
Abstract
It has been reported that 8-oxo-7,8-dihydro-guanosine (8-oxo-G), which is the main product of oxidative damage of DNA, can repair cyclobutane pyrimidine dimer (CPD) lesions when incorporated into DNA or RNA strands in proximity to such lesions. It has therefore been suggested that the 8-oxo-G nucleoside may have been a primordial precursor of present-day flavins in DNA or RNA repair. Because the electron transfer leading to the splitting of a thymine-thymine pair in a CPD lesion occurs in the photoexcited state, a reasonably long excited-state lifetime of 8-oxo-G is required. The neutral (protonated) form of 8-oxo-G exhibits a very short (sub-picosecond) intrinsic excited-state lifetime which is unfavorable for repair. It has therefore been argued that the anionic (deprotonated) form of 8-oxo-G, which exhibits a much longer excited-state lifetime, is more likely to be a suitable cofactor for DNA repair. Herein, we have investigated the exited-state quenching mechanisms in the hydrogen-bonded complexes of deprotonated 8-oxo-G- with adenine (A) and cytosine (C) using ab initio wave-function-based electronic-structure calculations. The calculated reaction paths and potential-energy profiles reveal the existence of barrierless electron-driven inter-base proton-transfer reactions which lead to low-lying S₁/S₀ conical intersections. The latter can promote ultrafast excited-state deactivation of the anionic base pairs. While the isolated deprotonated 8-oxo-G- nucleoside may have been an efficient primordial repair cofactor, the excited states of the 8-oxo-G--A and 8-oxo-G--C base pairs are likely too short-lived to be efficient electron-transfer repair agents.
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Affiliation(s)
- Xiuxiu Wu
- Department of Chemistry, Technische Universitat Munchen, Lichtenbergstr. 4, Garching D-85747, Germany.
| | - Tolga N V Karsili
- Department of Chemistry, Temple University, 130 Beury Hall, 1901 N. 13th St., Philadelphia, PA 19122, USA.
| | - Wolfgang Domcke
- Department of Chemistry, Technische Universitat Munchen, Lichtenbergstr. 4, Garching D-85747, Germany.
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21
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Banyasz A, Ketola TM, Muñoz-Losa A, Rishi S, Adhikary A, Sevilla MD, Martinez-Fernandez L, Improta R, Markovitsi D. UV-Induced Adenine Radicals Induced in DNA A-Tracts: Spectral and Dynamical Characterization. J Phys Chem Lett 2016; 7:3949-3953. [PMID: 27636653 PMCID: PMC5053904 DOI: 10.1021/acs.jpclett.6b01831] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Adenyl radicals generated in DNA single and double strands, (dA)20 and (dA)20·(dT)20, by one- and two-photon ionization by 266 nm laser pulses decay at 600 nm with half-times of 1.0 ± 0.1 and 4 ± 1 ms, respectively. Though ionization initially forms the cation radical, the radicals detected for (dA)20 are quantitatively identified as N6-deprotonated adenyl radicals by their absorption spectrum, which is computed quantum mechanically employing TD-DFT. Theoretical calculations show that deprotonation of the cation radical induces only weak spectral changes, in line with the spectra of the adenyl radical cation and the deprotonated radical trapped in low temperature glasses.
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Affiliation(s)
- Akos Banyasz
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | - Tiia-Maaria Ketola
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | - Aurora Muñoz-Losa
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
| | - Sunny Rishi
- Department of Chemistry, Oakland University, Rochester, MI 48303
| | - Amitava Adhikary
- Department of Chemistry, Oakland University, Rochester, MI 48303
| | - Michael D. Sevilla
- Department of Chemistry, Oakland University, Rochester, MI 48303
- Corresponding Authors. , ,
| | - Lara Martinez-Fernandez
- Istituto Biostrutture e Bioimmagini-Consiglio Nazionale delle Ricerche, Via Mezzocannone 16, I-80134 Napoli, Italy
| | - Roberto Improta
- Istituto Biostrutture e Bioimmagini-Consiglio Nazionale delle Ricerche, Via Mezzocannone 16, I-80134 Napoli, Italy
- Corresponding Authors. , ,
| | - Dimitra Markovitsi
- LIDYL, CEA, CNRS, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France
- Corresponding Authors. , ,
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