1
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Markovitsi D. Processes triggered in guanine quadruplexes by direct absorption of UV radiation: From fundamental studies toward optoelectronic biosensors. Photochem Photobiol 2024; 100:262-274. [PMID: 37365765 DOI: 10.1111/php.13826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Revised: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 06/28/2023]
Abstract
Guanine quadruplexes (GQs) are four-stranded DNA/RNA structures exhibiting an important polymorphism. During the past two decades, their study by time-resolved spectroscopy, from femtoseconds to milliseconds, associated to computational methods, shed light on the primary processes occurring when they absorb UV radiation. Quite recently, their utilization in label-free and dye-free biosensors was explored by a few groups. In view of such developments, this review discusses the outcomes of the fundamental studies that could contribute to the design of future optoelectronic biosensors using fluorescence or charge carriers stemming directly from GQs, without mediation of other molecules, as it is the currently the case. It explains how the excited state relaxation influences both the fluorescence intensity and the efficiency of low-energy photoionization, occurring via a complex mechanism. The corresponding quantum yields, determined with excitation at 266/267 nm, fall in the range of (3.0-9.5) × 10-4 and (3.2-9.2) × 10-3 , respectively. These values, significantly higher than the corresponding values found for duplexes, depend strongly on certain structural factors (molecularity, metal cations, peripheral bases, number of tetrads …) which intervene in the relaxation process. Accordingly, these features can be tuned to optimize the desired signal.
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Affiliation(s)
- Dimitra Markovitsi
- CNRS, Institut de Chimie Physique, UMR8000, Université Paris-Saclay, Orsay, France
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2
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Gustavsson T, Markovitsi D. The Ubiquity of High-Energy Nanosecond Fluorescence in DNA Duplexes. J Phys Chem Lett 2023; 14:2141-2147. [PMID: 36802626 DOI: 10.1021/acs.jpclett.2c03884] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
During the past few years, several studies reported that a significant part of the intrinsic fluorescence of DNA duplexes decays with surprisingly long lifetimes (1-3 ns) at wavelengths shorter than the ππ* emission of their monomeric constituents. This high-energy nanosecond emission (HENE), hardly discernible in the steady-state fluorescence spectra of most duplexes, was investigated by time-correlated single-photon counting. The ubiquity of HENE contrasts with the paradigm that the longest-lived excited states correspond to low-energy excimers/exciplexes. Interestingly, the latter were found to decay faster than the HENE. So far, the excited states responsible for HENE remain elusive. In order to foster future studies for their characterization, this Perspective presents a critical summary of the experimental observations and the first theoretical approaches. Moreover, some new directions for further work are outlined. Finally, the obvious need for computations of the fluorescence anisotropy considering the dynamic conformational landscape of duplexes is stressed.
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Affiliation(s)
- Thomas Gustavsson
- Université Paris-Saclay, CEA, CNRS, LIDYL, 91191 Gif-sur-Yvette, France
| | - Dimitra Markovitsi
- Université Paris-Saclay, CNRS, Institut de Chimie Physique, UMR8000, 91405 Orsay, France
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3
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Bauer B, Sharma R, Chergui M, Oppermann M. Exciton decay mechanism in DNA single strands: back-electron transfer and ultrafast base motions. Chem Sci 2022; 13:5230-5242. [PMID: 35655577 PMCID: PMC9093102 DOI: 10.1039/d1sc06450a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 04/09/2022] [Indexed: 12/03/2022] Open
Abstract
The photochemistry of DNA systems is characterized by the ultraviolet (UV) absorption of π-stacked nucleobases, resulting in exciton states delocalized over several bases. As their relaxation sensitively depends on local stacking conformations, disentangling the ensuing electronic and structural dynamics has remained an experimental challenge, despite their fundamental role in protecting the genome from potentially harmful UV radiation. Here we use transient absorption and transient absorption anisotropy spectroscopy with broadband femtosecond deep-UV pulses (250–360 nm) to resolve the exciton dynamics of UV-excited adenosine single strands under physiological conditions. Due to the exceptional deep-UV bandwidth and polarization sensitivity of our experimental approach, we simultaneously resolve the population dynamics, charge-transfer (CT) character and conformational changes encoded in the UV transition dipoles of the π-stacked nucleotides. Whilst UV excitation forms fully charge-separated CT excitons in less than 0.3 ps, we find that most decay back to the ground state via a back-electron transfer. Based on the anisotropy measurements, we propose that this mechanism is accompanied by a structural relaxation of the photoexcited base-stack, involving an inter-base rotation of the nucleotides. Our results finally complete the exciton relaxation mechanism for adenosine single strands and offer a direct view into the coupling of electronic and structural dynamics in aggregated photochemical systems. Despite its key role in DNA photochemistry, the decay mechanism of excitons in stacked bases has remained difficult to resolve. Ultrafast polarization spectroscopy now reveals a back-electron transfer and ultrafast base motions in adenosine strands.![]()
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Affiliation(s)
- Benjamin Bauer
- Laboratory of Ultrafast Spectroscopy (LSU), Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, ISIC-FSB CH-1015 Lausanne Switzerland
| | - Rahul Sharma
- Laboratory for Computation and Visualization in Mathematics and Mechanics, École Polytechnique Fédérale de Lausanne, MATH-FSB CH-1015 Lausanne Switzerland
| | - Majed Chergui
- Laboratory of Ultrafast Spectroscopy (LSU), Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, ISIC-FSB CH-1015 Lausanne Switzerland
| | - Malte Oppermann
- Laboratory of Ultrafast Spectroscopy (LSU), Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne, ISIC-FSB CH-1015 Lausanne Switzerland
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4
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Zuluaga C, Spata VA, Matsika S. Benchmarking Quantum Mechanical Methods for the Description of Charge-Transfer States in π-Stacked Nucleobases. J Chem Theory Comput 2020; 17:376-387. [PMID: 33346637 DOI: 10.1021/acs.jctc.0c00973] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Charge-transfer (CT) states are of special interest in photochemical research because they can facilitate chemical reactions through the rearrangement of electrons and subsequently chemical bonds in a molecular system. Of particular importance to this research is the transfer of electrons between π-stacked nucleobases in DNA because they play an important role in its photophysics and photochemistry. Computational methods are paramount for the study of CT states because of the current inability of experimental methods to easily detect such states. However, many ab-initio wavefunction-based and density functional theory (DFT) methods fail to accurately describe these CT states. Here, we benchmark how 40 different quantum mechanical methods describe the excited states of a guanine-thymine π-stacked nucleobase dimer system, both in 5'-TG-3' and 5'-GT-3' conformations. We find that the distance between the nucleobases plays a major role in the energy of the CT state and in the difference of the dipole moments between the CT and ground state. There is a larger range of values (and errors) for the energies of CT states compared to those of states localized on one nucleobase. Wavefunction-based methods have similar errors for the CT and localized valence states, while DFT methods are very sensitive to the amount of Hartree-Fock exchange. Long-range-corrected functionals with a careful balance of the Hartree-Fock exchange included can predict very accurate CT states and a balanced description with the localized states.
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Affiliation(s)
- Camilo Zuluaga
- Department of Chemistry, Temple University, 1901 N 13th Street, Philadelphia, Pennsylvania, United States
| | - Vincent A Spata
- Department of Chemistry, Temple University, 1901 N 13th Street, Philadelphia, Pennsylvania, United States
| | - Spiridoula Matsika
- Department of Chemistry, Temple University, 1901 N 13th Street, Philadelphia, Pennsylvania, United States
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5
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Rukin PS, Komarova KG, Fresch B, Collini E, Remacle F. Chirality of a rhodamine heterodimer linked to a DNA scaffold: an experimental and computational study. Phys Chem Chem Phys 2020; 22:7516-7523. [PMID: 32219241 DOI: 10.1039/d0cp00223b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The chiroptical properties of multi-chromophoric systems are governed by the intermolecular arrangement of the monomeric units. We report on a computational and experimental study of the linear optical properties and supramolecular structure of a rhodamine heterodimer assembled on a DNA scaffold. The experimental absorption and circular dichroism (CD) profiles confirm the dimer formation. Computationally, starting from low-cost DFT/TDDFT simulations of the bare dimer we attribute the measured -/+ CD sign sequence of the S1/S2 bands to a specific chiral conformation of the heterodimer. In the monomers, as typical for rhodamine dyes, the electric transition dipole of the lowest π-π* transition is parallel to the long axis of the xanthene planes. We show that in the heterodimer the sign sequence of the two CD bands is related to the orientation of these long axes. To account explicitly for environment effects, we use molecular dynamics (MD) simulations for characterizing the supramolecular structure of the two optical isomers tethered on DNA. Average absorption and CD-profiles were modeled using ab initio TDDFT calculations at the geometries sampled along a few nanosecond MD run. The absorption profiles computed for both optical isomers are in good agreement with the experimental absorption spectrum and do not allow one to discriminate between them. The computed averaged CD profiles provide the orientation of monomers in the enantiomer that is dominant under the experimental conditions.
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Affiliation(s)
- P S Rukin
- Theoretical Physical Chemistry, UR MolSys B6c, University of Liege, B4000, Liege, Belgium.
| | - K G Komarova
- Theoretical Physical Chemistry, UR MolSys B6c, University of Liege, B4000, Liege, Belgium.
| | - B Fresch
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy
| | - E Collini
- Department of Chemical Sciences, University of Padova, via Marzolo 1, 35131 Padova, Italy
| | - F Remacle
- Theoretical Physical Chemistry, UR MolSys B6c, University of Liege, B4000, Liege, Belgium.
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6
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Martinez-Fernandez L, Changenet P, Banyasz A, Gustavsson T, Markovitsi D, Improta R. Comprehensive Study of Guanine Excited State Relaxation and Photoreactivity in G-quadruplexes. J Phys Chem Lett 2019; 10:6873-6877. [PMID: 31613628 DOI: 10.1021/acs.jpclett.9b02740] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
G-quadruplexes (G4) are four-stranded DNA/RNA structures playing a key role in many biological functions and promising for nanotechnology applications. Here, combining theoretical calculations and multiscale time-resolved fluorescence, we describe, for the first time, an ensemble of photoactivated processes involving the guanines of the G4 core. We use as showcase the G4 formed by the human telomeric sequence GGG(TTAGGG)3 in the presence of Na+ ions. According to quantum mechanical/molecular mechanics calculations, the hyperchromism at the red part of the absorption spectrum, typical of G4 structures, arises mainly from the inner Na+ ions. Various relaxation pathways, leading to excited states localized on individual bases, neutral excimers, and excited charge transfer states between two guanines or a guanine and a thymine in the loop, are mapped. Their fingerprints are detected in the fluorescence anisotropies and the fluorescence decays, spanning five decades of time. Finally, a reaction funnel leading to guanine dimerization is identified.
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Affiliation(s)
| | - Pascale Changenet
- LIDYL, CEA, CNRS, Université Paris-Saclay , F-91191 Gif-sur-Yvette , France
- Laboratoire d'Optique et Biosciences, Institut Polytechnique de Paris , CNRS, INSERM, Université Paris-Saclay , 91128 Palaiseau cedex , France
| | - Akos Banyasz
- LIDYL, CEA, CNRS, Université Paris-Saclay , F-91191 Gif-sur-Yvette , France
| | - Thomas Gustavsson
- 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
| | - 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
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7
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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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8
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Dsouza R, Cheng X, Li Z, Miller RJD, Kochman MA. Oscillatory Photoelectron Signal of N-Methylmorpholine as a Test Case for the Algebraic-Diagrammatic Construction Method of Second Order. J Phys Chem A 2018; 122:9688-9700. [DOI: 10.1021/acs.jpca.8b10241] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Raison Dsouza
- Max Planck Institute for the Structure and Dynamics of Matter, Bldg. 99 (CFEL), Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Xinxin Cheng
- Max Planck Institute for the Structure and Dynamics of Matter, Bldg. 99 (CFEL), Luruper Chaussee 149, 22761 Hamburg, Germany
- Hamburg Centre for Ultrafast Imaging (CUI), Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Zheng Li
- Max Planck Institute for the Structure and Dynamics of Matter, Bldg. 99 (CFEL), Luruper Chaussee 149, 22761 Hamburg, Germany
| | - R. J. Dwayne Miller
- Max Planck Institute for the Structure and Dynamics of Matter, Bldg. 99 (CFEL), Luruper Chaussee 149, 22761 Hamburg, Germany
- Hamburg Centre for Ultrafast Imaging (CUI), Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Department of Chemistry and Physics, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
| | - Michał Andrzej Kochman
- Department of Physics, Chemistry and Biology (IFM), Linköping University, 581 83 Linköping, Sweden
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9
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Stange UC, Temps F. Ultrafast electronic deactivation of UV-excited adenine and its ribo- and deoxyribonucleosides and -nucleotides: A comparative study. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.08.031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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10
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Szabla R, Kruse H, Stadlbauer P, Šponer J, Sobolewski AL. Sequential electron transfer governs the UV-induced self-repair of DNA photolesions. Chem Sci 2018; 9:3131-3140. [PMID: 29732095 PMCID: PMC5916108 DOI: 10.1039/c8sc00024g] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Accepted: 02/22/2018] [Indexed: 01/09/2023] Open
Abstract
Cyclobutane pyrimidine dimers (CpDs) are among the most common DNA lesions occurring due to the interaction with ultraviolet light. While photolyases have been well known as external factors repairing CpDs, the intrinsic self-repairing capabilities of the GAT 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 T DNA sequence were discovered only recently and are still largely obscure. Here, we elucidate the mechanistic details of this self-repair process by means of MD simulations and QM/MM computations involving the algebraic diagrammatic construction to the second order [ADC(2)] method. We show that local UV-excitation of guanine may be followed by up to three subsequent electron transfers, which may eventually enable efficient CpD ring opening when the negative charge resides on the T 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 T dimer. Consequently, the molecular mechanism of GAT 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 T self-repair can be envisaged as sequential electron transfer (SET) occurring downhill along the slope of the S1 potential energy surface. Even though the general features of the SET mechanism are retained in both of the studied stacked conformers, our optimizations of different S1/S0 state crossings revealed minor differences which could influence their self-repair efficiencies. We expect that such assessment of the availability and efficiency of the SET process in other DNA oligomers could hint towards other sequences exhibiting similar photochemical properties. Such explorations will be particularly fascinating in the context of the origins of biomolecules on Earth, owing to the lack of external repairing factors in the Archean age.
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Affiliation(s)
- Rafał Szabla
- Institute of Physics , Polish Academy of Sciences , Al. Lotników 32/46 , PL-02668 Warsaw , Poland.,Institute of Biophysics of the Czech Academy of Sciences , Královopolská 135 , 61265 Brno , Czech Republic .
| | - Holger Kruse
- Institute of Biophysics of the Czech Academy of Sciences , Královopolská 135 , 61265 Brno , Czech Republic .
| | - Petr Stadlbauer
- Institute of Biophysics of the Czech Academy of Sciences , Královopolská 135 , 61265 Brno , Czech Republic . .,Regional Centre of Advanced Technologies and Materials , Department of Physical Chemistry , Faculty of Science , Palacký University , 17. Listopadu 1192/12 , 77146 Olomouc , Czech Republic
| | - Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences , Královopolská 135 , 61265 Brno , Czech Republic .
| | - Andrzej L Sobolewski
- Institute of Physics , Polish Academy of Sciences , Al. Lotników 32/46 , PL-02668 Warsaw , Poland
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11
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Skowron DJ, Zhang Y, Beckstead AA, Remington JM, Strawn M, Kohler B. Subnanosecond Emission Dynamics of AT DNA Oligonucleotides. Chemphyschem 2016; 17:3558-3569. [PMID: 27582073 DOI: 10.1002/cphc.201600566] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 08/30/2016] [Indexed: 01/16/2023]
Abstract
UV radiation creates excited electronic states in DNA that can decay to mutagenic photoproducts. When excited states return to the electronic ground state, photochemical injury is avoided. Understanding of the available relaxation pathways has advanced rapidly during the past decade, but there has been persistent uncertainty, and even controversy, over how to compare results from transient absorption and time-resolved emission experiments. Here, emission from single- and double-stranded AT DNA compounds excited at 265 nm was studied in aqueous solution using the time-correlated single photon counting technique. There is quantitative agreement between the emission lifetimes ranging from 50 to 200 ps and ones measured in transient absorption experiments, demonstrating that both techniques probe the same excited states. The results indicate that excitations with lifetimes of more than a few picoseconds are weakly emissive excimer and charge transfer states. Only a minute fraction of excitations persist beyond 1 ns in AT DNA strands at room temperature.
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Affiliation(s)
- David J Skowron
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717-3400, USA
| | - Yuyuan Zhang
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717-3400, USA
| | - Ashley A Beckstead
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717-3400, USA
| | - Jacob M Remington
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717-3400, USA
| | - Madison Strawn
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717-3400, USA
| | - Bern Kohler
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT, 59717-3400, USA
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12
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Li Q, Giussani A, Segarra-Martí J, Nenov A, Rivalta I, Voityuk AA, Mukamel S, Roca-Sanjuán D, Garavelli M, Blancafort L. Multiple Decay Mechanisms and 2D-UV Spectroscopic Fingerprints of Singlet Excited Solvated Adenine-Uracil Monophosphate. Chemistry 2016; 22:7497-507. [PMID: 27113273 PMCID: PMC5021121 DOI: 10.1002/chem.201505086] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Indexed: 02/04/2023]
Abstract
The decay channels of singlet excited adenine uracil monophosphate (ApU) in water are studied with CASPT2//CASSCF:MM potential energy calculations and simulation of the 2D-UV spectroscopic fingerprints with the aim of elucidating the role of the different electronic states of the stacked conformer in the excited state dynamics. The adenine (1) La state can decay without a barrier to a conical intersection with the ground state. In contrast, the adenine (1) Lb and uracil S(U) states have minima that are separated from the intersections by sizeable barriers. Depending on the backbone conformation, the CT state can undergo inter-base hydrogen transfer and decay to the ground state through a conical intersection, or it can yield a long-lived minimum stabilized by a hydrogen bond between the two ribose rings. This suggests that the (1) Lb , S(U) and CT states of the stacked conformer may all contribute to the experimental lifetimes of 18 and 240 ps. We have also simulated the time evolution of the 2D-UV spectra and provide the specific fingerprint of each species in a recommended probe window between 25 000 and 38 000 cm(-1) in which decongested, clearly distinguishable spectra can be obtained. This is expected to allow the mechanistic scenarios to be discerned in the near future with the help of the corresponding experiments. Our results reveal the complexity of the photophysics of the relatively small ApU system, and the potential of 2D-UV spectroscopy to disentangle the photophysics of multichromophoric systems.
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Affiliation(s)
- Quansong Li
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry, Beijing Institute of Technology, 100081, Beijing, P.R. China
| | - Angelo Giussani
- Dipartimento di Chimica "G. Ciamician", Università di Bologna, Via Selmi 2, 40126, Bologna, Italy
| | - Javier Segarra-Martí
- Dipartimento di Chimica "G. Ciamician", Università di Bologna, Via Selmi 2, 40126, Bologna, Italy
| | - Artur Nenov
- Dipartimento di Chimica "G. Ciamician", Università di Bologna, Via Selmi 2, 40126, Bologna, Italy
| | - Ivan Rivalta
- Univ Lyon, >Ens de Lyon, CNRS, Université Lyon 1, Laboratoire de Chimie UMR 5182, 69342, Lyon, France
| | - Alexander A Voityuk
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Campus de Montilvi, 17071, Girona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08010, Barcelona, Spain
| | - Shaul Mukamel
- Department of Chemistry, University of California, Irvine, California, 92697-2025, USA
| | - Daniel Roca-Sanjuán
- Instituto de Ciencia Molecular, Universitat de València, P. O. Box 22085, 46071, Valencia, Spain
| | - Marco Garavelli
- Dipartimento di Chimica "G. Ciamician", Università di Bologna, Via Selmi 2, 40126, Bologna, Italy.
- Univ Lyon, >Ens de Lyon, CNRS, Université Lyon 1, Laboratoire de Chimie UMR 5182, 69342, Lyon, France.
| | - Lluís Blancafort
- Institut de Química Computacional i Catàlisi and Departament de Química, Universitat de Girona, Campus de Montilvi, 17071, Girona, Spain.
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13
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Tuna D, Udvarhelyi A, Sobolewski AL, Domcke W, Domratcheva T. Onset of the Electronic Absorption Spectra of Isolated and π-Stacked Oligomers of 5,6-Dihydroxyindole: An Ab Initio Study of the Building Blocks of Eumelanin. J Phys Chem B 2016; 120:3493-502. [PMID: 27005558 DOI: 10.1021/acs.jpcb.6b01793] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Eumelanin is a naturally occurring skin pigment which is responsible for developing a suntan. The complex structure of eumelanin consists of π-stacked oligomers of various indole derivatives, such as the monomeric building block 5,6-dihydroxyindole (DHI). In this work, we present an ab initio wave-function study of the absorption behavior of DHI oligomers and of doubly and triply π-stacked species of these oligomers. We have simulated the onset of the electronic absorption spectra by employing the MP2 and the linear-response CC2 methods. Our results demonstrate the effect of an increasing degree of oligomerization of DHI and of an increasing degree of π-stacking of DHI oligomers on the onset of the absorption spectra and on the degree of red-shift toward the visible region of the spectrum. We find that π-stacking of DHI and its oligomers substantially red-shifts the onset of the absorption spectra. Our results also suggest that the optical properties of biological eumelanin cannot be simulated by considering the DHI building blocks alone, but instead the building blocks indole-semiquinone and indole-quinone have to be considered as well. This study contributes to advancing the understanding of the complex photophysics of the eumelanin biopolymer.
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Affiliation(s)
- Deniz Tuna
- Department of Chemistry, Technische Universität München , 85747 Garching, Germany
| | - Anikó Udvarhelyi
- Department of Biomolecular Mechanisms, Max-Planck-Institut für Medizinische Forschung , 69120 Heidelberg, Germany
| | | | - Wolfgang Domcke
- Department of Chemistry, Technische Universität München , 85747 Garching, Germany
| | - Tatiana Domratcheva
- Department of Biomolecular Mechanisms, Max-Planck-Institut für Medizinische Forschung , 69120 Heidelberg, Germany
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14
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Spata VA, Lee W, Matsika S. Excimers and Exciplexes in Photoinitiated Processes of Oligonucleotides. J Phys Chem Lett 2016; 7:976-984. [PMID: 26911276 DOI: 10.1021/acs.jpclett.5b02756] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A lot has been learned about the physical and chemical transformations that originate from the absorption of light by DNA, and computational chemistry has played a critical role in revealing the mechanisms of how these transformations occur. Nucleic acids consist of chromophores interacting via π stacking and hydrogen bonding. The fate of these systems after they absorb light is determined by the interplay and competition between pathways involving one chromophore or interacting chromophores. This Perspective highlights the role of π stacking in photophysical and photochemical processes in oligonucleotides and reveals the importance of excimers and exciplexes. Special types of excimers/exciplexes, characterized as bonded excimers/exciplexes, are also found to be important.
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Affiliation(s)
- Vincent A Spata
- Department of Chemistry, Temple University , Philadelphia, Pennsylvania 19122, United States
| | - Wook Lee
- Department of Chemistry, Temple University , Philadelphia, Pennsylvania 19122, United States
| | - Spiridoula Matsika
- Department of Chemistry, Temple University , Philadelphia, Pennsylvania 19122, United States
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