1
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Tsizin S, Ban L, Chasovskikh E, Yoder BL, Signorell R. Valence photoelectron imaging of molecular oxybenzone. Phys Chem Chem Phys 2024; 26:19236-19246. [PMID: 38957915 PMCID: PMC11253247 DOI: 10.1039/d3cp06224d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2023] [Accepted: 06/18/2024] [Indexed: 07/04/2024]
Abstract
An oxybenzone molecule in the gas phase was characterized by mass spectrometry and angle-resolved photoelectron spectroscopy, using both single and multiphoton ionization schemes. A tabletop high harmonic generation source with a monochromator was used for single-photon ionization of oxybenzone with photon energies of up to 35.7 eV. From this, vertical ionization and appearance energies, as well as energy-dependent anisotropy parameters were retrieved and compared with the results from DFT calculations. For two-photon ionization using 4.7 eV light, we found a higher appearance energy than in the extreme ultraviolet (EUV) case, highlighting the possible influence of an intermediate state on the photoionization process. We found no differences in the mass spectra when ionizing oxybenzone by single-photons between 17.2 and 35.7 eV. However, for the multiphoton ionization, the fragmentation process was found to be sensitive to the photoionization order and laser intensity. The "softest" method was found to be two-photon ionization using 4.7 eV light, which led to no measurable fragmentation up to an intensity of 5 × 1012 W cm-2.
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Affiliation(s)
- Svetlana Tsizin
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2., CH-8093 Zürich, Switzerland.
| | - Loren Ban
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2., CH-8093 Zürich, Switzerland.
| | - Egor Chasovskikh
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2., CH-8093 Zürich, Switzerland.
| | - Bruce L Yoder
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2., CH-8093 Zürich, Switzerland.
| | - Ruth Signorell
- Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2., CH-8093 Zürich, Switzerland.
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2
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Uddin IA, Stec E, Papadantonakis GA. Ionization Patterns and Chemical Reactivity of Cytosine-Guanine Watson-Crick Pairs. Chemphyschem 2024; 25:e202300946. [PMID: 38381922 DOI: 10.1002/cphc.202300946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 02/15/2024] [Accepted: 02/21/2024] [Indexed: 02/23/2024]
Abstract
Gas-phase and aqueous vertical ionization potentials, vIPgas and vIPaq respectively and measurements of the molecular electrostatic and local ionization maps calculated at the DFT/B3LYP-D3/ 6-311+G** level of theory and the C-PCM reaction field model for single- and double-stranded CpG and 5MeCpG pairs show that the vIPaq for single- and double-stranded pairs of C-G and 5MeC-G are practically the same, in the range of 5.79 to 5.81 eV. The aqueous adiabatic ionization potentials for single-stranded CpG and 5MeCpG are 5.52 eV and 5.51 eV respectively and they reflect the nuclear reorganization that takes place after the abstraction of the electron. The aqueous adiabatic ionization energy values that correspond to the CpG+. radical cation and the hydrated electron, e-,, being at infinite distance, adIPaq+Vo, are 3.92 eV and 3.91 eV respectively with (Vo=-1.6 eV) Analysis of data suggest that the HOMO-LUMO energy gap in the hard/soft-acid/base (HSAB) concept cannot be used a priori to determine the effect of cytosine methylation on the guanine enhanced oxidative damage in DNA.
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Affiliation(s)
- Ismihan A Uddin
- University of Illinois Chicago, Department of Chemistry, 845 W. Taylor St. Room 4506 SES, Chicago, IL. 60607
- Midwestern University Chicago, College of Osteopathic Medicine and formerly at University of Illinois Chicago, Department of Chemistry, 555 31st St., Downers Grove, IL 60515
- Midwestern University Chicago, College of Osteopathic Medicine and formerly at University of Illinois Chicago, Department of Chemistry, 555 31st St., Downers Grove, IL 60515
| | - Ewa Stec
- University of Illinois Chicago, Department of Chemistry, 845 W. Taylor St. Room 4506 SES, Chicago, IL. 60607
- Midwestern University Chicago, College of Osteopathic Medicine and formerly at University of Illinois Chicago, Department of Chemistry, 555 31st St., Downers Grove, IL 60515
| | - George A Papadantonakis
- University of Illinois Chicago, Department of Chemistry, 845 W. Taylor St. Room 4506 SES, Chicago, IL. 60607
- Midwestern University Chicago, College of Osteopathic Medicine and formerly at University of Illinois Chicago, Department of Chemistry, 555 31st St., Downers Grove, IL 60515
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3
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Ling CCH, Chan WX, Siow JX, Loh ZH. Ultrafast Vibrational Wave Packet Dynamics of the Aqueous Guanine Radical Anion Induced by Photodetachment. J Phys Chem A 2024; 128:626-635. [PMID: 38207335 DOI: 10.1021/acs.jpca.3c08232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2024]
Abstract
Studying the ultrafast dynamics of ionized aqueous biomolecules is important for gaining an understanding of the interaction of ionizing radiation with biological matter. Guanine plays an essential role in biological systems as one of the four nucleobases that form the building blocks of deoxyribonucleic acid (DNA). Guanine radicals can induce oxidative damage to DNA, particularly due to the lower ionization potential of guanine compared to the other nucleobases, sugars, and phosphate groups that are constituents of DNA. This study utilizes femtosecond optical pump-probe spectroscopy to observe the ultrafast vibrational wave packet dynamics of the guanine radical anion launched by photodetachment of the aqueous guanine dianion. The vibrational wave packet motion is resolved into 11 vibrational modes along which structural reorganization occurs upon photodetachment. These vibrational modes are assigned with the aid of density functional theory (DFT) calculations. Our work sheds light on the ultrafast vibrational dynamics following the ionization of nucleobases in an aqueous medium.
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Affiliation(s)
- Christine Chun Hui Ling
- School of Chemistry, Chemical Engineering and Biotechnology, and School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Wei Xin Chan
- School of Chemistry, Chemical Engineering and Biotechnology, and School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Jing Xuan Siow
- School of Chemistry, Chemical Engineering and Biotechnology, and School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
| | - Zhi-Heng Loh
- School of Chemistry, Chemical Engineering and Biotechnology, and School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, 637371, Singapore
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4
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Makurat S, Yuan Q, Czub J, Chomicz-Mańka L, Cao W, Wang XB, Rak J. Guanosine Dianions Hydrated by One to Four Water Molecules. J Phys Chem Lett 2022; 13:3230-3236. [PMID: 35380844 PMCID: PMC9014458 DOI: 10.1021/acs.jpclett.2c00512] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Accepted: 03/29/2022] [Indexed: 06/14/2023]
Abstract
Intermolecular interactions such as those present in molecule···water complexes may profoundly influence the physicochemical properties of molecules. Here, we carried out an experimental-computational study on doubly deprotonated guanosine monophosphate···water clusters, [dGMP - 2H]2-·nH2O (n = 1-4), using a combination of negative anion photoelectron spectroscopy (NIPES) with molecular dynamics (MD) and quantum chemical (QM) calculations. Successive addition of water molecules to [dGMP - 2H]2- increases the experimental adiabatic detachment (ADE) and vertical detachment energy (VDE) by 0.5-0.1 eV, depending on the cluster size. In order to choose the representative conformations, we combined MD simulations with a clustering procedure to identify low energy geometries for which ADEs and VDEs were computed at the CAM-B3LYP/6-31++G(d,p) level. Our results demonstrate that the assumed approach leads to sound geometries and energetics of the studied microsolvates since the calculated ADEs and VDEs are in pretty good agreement with the experimental characteristics. The evolution of hydrogen bonding with cluster size indicates the possibility of the occurrence of proton transfer for clusters comprising a larger number of water molecules.
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Affiliation(s)
- Samanta Makurat
- Faculty
of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Qinqin Yuan
- Physical
Sciences Division, Pacific Northwest National
Laboratory, Richland, Washington 99352, United States
- Department
of Chemistry, Anhui University, Hefei, Anhui 230601, China
| | - Jacek Czub
- Department
of Physical Chemistry, Gdańsk University
of Technology, Narutowicza
11/12, Gdańsk 80-233, Poland
- BioTechMed
Center, Gdańsk University of Technology, Narutowicza 11/12, Gdańsk 80-233, Poland
| | - Lidia Chomicz-Mańka
- Faculty
of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Wenjin Cao
- Physical
Sciences Division, Pacific Northwest National
Laboratory, Richland, Washington 99352, United States
| | - Xue-Bin Wang
- Physical
Sciences Division, Pacific Northwest National
Laboratory, Richland, Washington 99352, United States
| | - Janusz Rak
- Faculty
of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
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5
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Yuan Q, Chomicz-Mańka L, Makurat S, Cao W, Rak J, Wang XB. Photoelectron Spectroscopy and Theoretical Investigations of Gaseous Doubly Deprotonated 2'-Deoxynucleoside 5'-Monophosphate Dianions. J Phys Chem Lett 2021; 12:9463-9469. [PMID: 34558897 DOI: 10.1021/acs.jpclett.1c02678] [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: 06/13/2023]
Abstract
A better understanding of the mechanism of oxidative DNA damage requires obtaining a molecular level description of nucleotides in various charge states. Herein, we report a systematic photoelectron spectroscopy and theoretical investigation of the electronic and geometric structures of four doubly deprotonated 2'-deoxynucleoside 5'-monophosphate dianions, the smallest quintessential DNA building block. These dianions are intrinsically stable with their adiabatic/vertical detachment energies (ADE/VDE) ranging from 0.85/1.07 (A) and 1.05/1.30 (G) to 1.20/1.50 (C) and 1.80/2.10 eV (T). The repulsive Coulomb barrier against electron detachment is 2.0 eV for purines and 2.5 eV for pyrimidines. Dianions are deprotonated at the phosphate group and the amino group of a nucleobase. The π-type HOMO orbital resides on the nucleobase moiety for each dianion. This spatial distribution of HOMO suggests that the most loosely bound electron is detached along the direction perpendicular to the nucleobase. When combined with the previous results, this work makes complete the depiction of basic building blocks of DNA at the molecular level.
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Affiliation(s)
- Qinqin Yuan
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Lidia Chomicz-Mańka
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Samanta Makurat
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Wenjin Cao
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
| | - Janusz Rak
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Xue-Bin Wang
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99352, United States
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6
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Castellani ME, Verlet JRR. Intramolecular Photo-Oxidation as a Potential Source to Probe Biological Electron Damage: A Carboxylated Adenosine Analogue as Case Study. Molecules 2021; 26:2877. [PMID: 34067988 PMCID: PMC8152231 DOI: 10.3390/molecules26102877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/05/2021] [Accepted: 05/10/2021] [Indexed: 11/16/2022] Open
Abstract
A carboxylated adenosine analog (C-Ado-) has been synthesized and probed via time-resolved photoelectron spectroscopy in order to induce intra-molecular charge transfer from the carboxylic acid moiety to the nucleobase. Intra-molecular charge transfer can be exploited as starting point to probe low-energy electron (LEE) damage in DNA and its derivatives. Time-dependent density functional theory (TD-DFT) calculations at the B3LYP-6311G level of theory have been performed to verify that the highest occupied molecular orbital (HOMO) was located on carboxylic acid and that the lowest occupied molecular orbital (LUMO) was on the nucleobase. Hence, the carboxylic acid could work as electron source, whilst the nucleobase could serve the purpose of electron acceptor. The dynamics following excitation at 4.66 eV (266 nm) were probed using time-resolved photoelectron spectroscopy using probes at 1.55 eV (800 nm) and 3.10 eV (400 nm). The data show rapid decay of the excited state population and, based on the similarity of the overall dynamics to deoxy-adenosine monophosphate (dAMP-), it appears that the dominant decay mechanism is internal conversion following 1ππ* excitation of the nucleobase, rather than charge-transfer from the carboxylic acid to the nucleobase.
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7
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Castellani ME, Avagliano D, Verlet JRR. Ultrafast Dynamics of the Isolated Adenosine-5'-triphosphate Dianion Probed by Time-Resolved Photoelectron Imaging. J Phys Chem A 2021; 125:3646-3652. [PMID: 33882670 DOI: 10.1021/acs.jpca.1c01646] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The excited state dynamics of the doubly deprotonated dianion of adenosine-5'-triphosphate, [ATP-H2]2-, has been spectroscopically explored by time-resolved photoelectron spectroscopy following excitation at 4.66 eV. Time-resolved photoelectron spectra show that two competing processes occur for the initially populated 1ππ* state. The first is rapid electron emission by tunneling through a repulsive Coulomb barrier as the 1ππ* state is a resonance. The second is nuclear motion on the 1ππ* state surface leading to an intermediate that no longer tunnels and subsequently decays by internal conversion to the ground electronic state. The spectral signatures of the features are similar to those observed for other adenine-derivatives, suggesting that this nucleobase is quite insensitive to the nearby negative charges localized on the phosphates, except of course for the appearance of the additional electron tunneling channel, which is open in the dianion.
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Affiliation(s)
| | - Davide Avagliano
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Strasse 17 1090 Vienna, Austria
| | - Jan R R Verlet
- Department of Chemistry, Durham University, DH1 3LE Durham, U.K
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8
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Castellani ME, Avagliano D, González L, Verlet JRR. Site-Specific Photo-oxidation of the Isolated Adenosine-5'-triphosphate Dianion Determined by Photoelectron Imaging. J Phys Chem Lett 2020; 11:8195-8201. [PMID: 32886886 DOI: 10.1021/acs.jpclett.0c02089] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Photoelectron imaging of the isolated adenosine-5'-triphosphate dianion excited to the 1ππ* states reveals that electron emission is predominantly parallel to the polarization axis of the light and arises from subpicosecond electron tunneling through the repulsive Coulomb barrier (RCB). The computed RCB shows that the most probable electron emission site is on the amino group of adenine. This is consistent with the photoelectron imaging: excitation to the 1ππ* states leads to an aligned ensemble distributed predominantly parallel to the long axis of adenine; the subsequent electron tunneling site is along this axis; and the negatively charged phosphate groups guide the outgoing electron mostly along this axis at long range. Imaging of electron tunneling from polyanions combined with computational chemistry may offer a general route for probing the intrinsic photo-oxidation site and dynamics as well as the overall structure of complex isolated species.
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Affiliation(s)
| | - Davide Avagliano
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
| | - Leticia González
- Institute of Theoretical Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 17, 1090 Vienna, Austria
| | - Jan R R Verlet
- Department of Chemistry, Durham University, Durham DH1 3LE, United Kingdom
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9
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Cercola R, Uleanya KO, Dessent CEH. Electron detachment dynamics of the iodide-guanine cluster: does ionization occur from the iodide or from guanine? Mol Phys 2019. [DOI: 10.1080/00268976.2019.1679402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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10
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Roy A, Seidel R, Kumar G, Bradforth SE. Exploring Redox Properties of Aromatic Amino Acids in Water: Contrasting Single Photon vs Resonant Multiphoton Ionization in Aqueous Solutions. J Phys Chem B 2018. [DOI: 10.1021/acs.jpcb.7b11762] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Anirban Roy
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Robert Seidel
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - Gaurav Kumar
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
| | - Stephen E. Bradforth
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482, United States
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11
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Eichler DR, Hamann HA, Harte KA, Papadantonakis GA. Hydration effects on the photoionization energy of 2′-deoxyguanosine 5′-phosphate and activation barriers for guanine methylation by carcinogenic methane diazonium ions. Chem Phys Lett 2017. [DOI: 10.1016/j.cplett.2017.05.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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12
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Seidel R, Winter B, Bradforth SE. Valence Electronic Structure of Aqueous Solutions: Insights from Photoelectron Spectroscopy. Annu Rev Phys Chem 2016; 67:283-305. [PMID: 27023757 DOI: 10.1146/annurev-physchem-040513-103715] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The valence orbital electron binding energies of water and of embedded solutes are crucial quantities for understanding chemical reactions taking place in aqueous solution, including oxidation/reduction, transition-metal coordination, and radiation chemistry. Their experimental determination based on liquid-photoelectron spectroscopy using soft X-rays is described, and we provide an overview of valence photoelectron spectroscopy studies reported to date. We discuss principal experimental aspects and several theoretical approaches to compute the measured binding energies of the least tightly bound molecular orbitals. Solutes studied are presented chronologically, from simple electrolytes, via transition-metal ion solutions and several organic and inorganic molecules, to biologically relevant molecules, including aqueous nucleotides and their components. In addition to the lowest vertical ionization energies, the measured valence photoelectron spectra also provide information on adiabatic ionization energies and reorganization energies for the oxidation (ionization) half-reaction. For solutes with low solubility, resonantly enhanced ionization provides a promising alternative pathway.
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Affiliation(s)
- Robert Seidel
- Institute of Methods for Material Development, Helmholtz-Zentrum Berlin, D-12489 Berlin, Germany; ,
| | - Bernd Winter
- Institute of Methods for Material Development, Helmholtz-Zentrum Berlin, D-12489 Berlin, Germany; ,
| | - Stephen E Bradforth
- Department of Chemistry, University of Southern California, Los Angeles, California 90089-0482;
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13
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Stavros VG, Verlet JRR. Gas-Phase Femtosecond Particle Spectroscopy: A Bottom-Up Approach to Nucleotide Dynamics. Annu Rev Phys Chem 2016; 67:211-32. [PMID: 26980306 DOI: 10.1146/annurev-physchem-040215-112428] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We summarize how gas-phase ultrafast charged-particle spectroscopy has been used to provide an understanding of the photophysics of DNA building blocks. We focus on adenine and discuss how, following UV excitation, specific interactions determine the fates of its excited states. The dynamics can be probed using a systematic bottom-up approach that provides control over these interactions and that allows ever-larger complexes to be studied. Starting from a chromophore in adenine, the excited state decay mechanisms of adenine and chemically substituted or clustered adenine are considered and then extended to adenosine mono-, di-, and trinucleotides. We show that the gas-phase approach can offer exquisite insight into the dynamics observed in aqueous solution, but we also highlight stark differences. An outlook is provided that discusses some of the most promising developments in this bottom-up approach.
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Affiliation(s)
- Vasilios G Stavros
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, United Kingdom;
| | - Jan R R Verlet
- Department of Chemistry, University of Durham, Durham, DH1 3LE, United Kingdom;
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14
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Pluhařová E, Slavíček P, Jungwirth P. Modeling photoionization of aqueous DNA and its components. Acc Chem Res 2015; 48:1209-17. [PMID: 25738773 DOI: 10.1021/ar500366z] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Radiation damage to DNA is usually considered in terms of UVA and UVB radiation. These ultraviolet rays, which are part of the solar spectrum, can indeed cause chemical lesions in DNA, triggered by photoexcitation particularly in the UVB range. Damage can, however, be also caused by higher energy radiation, which can ionize directly the DNA or its immediate surroundings, leading to indirect damage. Thanks to absorption in the atmosphere, the intensity of such ionizing radiation is negligible in the solar spectrum at the surface of Earth. Nevertheless, such an ionizing scenario can become dangerously plausible for astronauts or flight personnel, as well as for persons present at nuclear power plant accidents. On the beneficial side, ionizing radiation is employed as means for destroying the DNA of cancer cells during radiation therapy. Quantitative information about ionization of DNA and its components is important not only for DNA radiation damage, but also for understanding redox properties of DNA in redox sensing or labeling, as well as charge migration along the double helix in nanoelectronics applications. Until recently, the vast majority of experimental and computational data on DNA ionization was pertinent to its components in the gas phase, which is far from its native aqueous environment. The situation has, however, changed for the better due to the advent of photoelectron spectroscopy in liquid microjets and its most recent application to photoionization of aqueous nucleosides, nucleotides, and larger DNA fragments. Here, we present a consistent and efficient computational methodology, which allows to accurately evaluate ionization energies and model photoelectron spectra of aqueous DNA and its individual components. After careful benchmarking, the method based on density functional theory and its time-dependent variant with properly chosen hybrid functionals and polarizable continuum solvent model provides ionization energies with accuracy of 0.2-0.3 eV, allowing for faithful modeling and interpretation of DNA photoionization. The key finding is that the aqueous medium is remarkably efficient in screening the interactions within DNA such that, unlike in the gas phase, ionization of a base, nucleoside, or nucleotide depends only very weakly on the particular DNA context. An exception is the electronic interaction between neighboring bases which can lead to sequence-specific effects, such as a partial delocalization of the cationic hole upon ionization enabled by presence of adjacent bases of the same type.
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Affiliation(s)
- Eva Pluhařová
- Institute
of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
| | - Petr Slavíček
- University of Chemistry and Technology, Department
of Physical Chemistry, Technická 5, 16628 Prague 6, Czech Republic
| | - Pavel Jungwirth
- Institute
of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, Flemingovo nám. 2, 16610 Prague 6, Czech Republic
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15
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Schroeder CA, Pluhařová E, Seidel R, Schroeder WP, Faubel M, Slavíček P, Winter B, Jungwirth P, Bradforth SE. Oxidation half-reaction of aqueous nucleosides and nucleotides via photoelectron spectroscopy augmented by ab initio calculations. J Am Chem Soc 2014; 137:201-9. [PMID: 25551179 DOI: 10.1021/ja508149e] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Oxidative damage to DNA and hole transport between nucleobases in oxidized DNA are important processes in lesion formation for which surprisingly poor thermodynamic data exist, the relative ease of oxidizing the four nucleobases being one such example. Theoretical simulations of radiation damage and charge transport in DNA depend on accurate values for vertical ionization energies (VIEs), reorganization energies, and standard reduction potentials. Liquid-jet photoelectron spectroscopy can be used to directly study the oxidation half-reaction. The VIEs of nucleic acid building blocks are measured in their native buffered aqueous environment. The experimental investigation of purine and pyrimidine nucleotides, nucleosides, pentose sugars, and inorganic phosphate demonstrates that photoelectron spectra of nucleotides arise as a spectral sum over their individual chemical components; that is, the electronic interactions between each component are effectively screened from one another by water. Electronic structure theory affords the assignment of the lowest energy photoelectron band in all investigated nucleosides and nucleotides to a single ionizing transition centered solely on the nucleobase. Thus, combining the measured VIEs with theoretically determined reorganization energies allows for the spectroscopic determination of the one-electron redox potentials that have been difficult to establish via electrochemistry.
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Affiliation(s)
- Christi A Schroeder
- Department of Chemistry, University of Southern California , Los Angeles, California 90089-0482, United States
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16
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Chatterley AS, West CW, Roberts GM, Stavros VG, Verlet JRR. Mapping the Ultrafast Dynamics of Adenine onto Its Nucleotide and Oligonucleotides by Time-Resolved Photoelectron Imaging. J Phys Chem Lett 2014; 5:843-848. [PMID: 26274076 DOI: 10.1021/jz500264c] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The intrinsic photophysics of nucleobases and nucleotides following UV absorption presents a key reductionist step toward understanding the complex photodamage mechanisms occurring in DNA. The decay mechanism of adenine in particular has been the focus of intense investigation, as has how these correlate to those of its more biologically relevant nucleotide and oligonucleotides in aqueous solution. Here, we report on time-resolved photoelectron imaging of the deprotonated 3'-deoxy-adenosine-5'-monophosphate nucleotide and the adenosine di- and trinucleotides. Through a comparison of gas- and solution-phase experiments and available theoretical studies, the dynamics of the base are shown to be relatively insensitive to the surrounding environment. The decay mechanism primarily involves internal conversion from the initially populated (1)ππ* states to the ground state. The relaxation dynamics of the adenosine oligonucleotides are similar to those of the nucleobase, in contrast to the aqueous oligonucleotides, where a fraction of the ensemble forms long-lived excimer states.
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Affiliation(s)
- Adam S Chatterley
- †Department of Chemistry, University of Durham, Durham DH1 3LE, United Kingdom
- ‡Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Christopher W West
- †Department of Chemistry, University of Durham, Durham DH1 3LE, United Kingdom
| | - Gareth M Roberts
- ‡Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Vasilios G Stavros
- ‡Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Jan R R Verlet
- †Department of Chemistry, University of Durham, Durham DH1 3LE, United Kingdom
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17
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Chatterley AS, West CW, Stavros VG, Verlet JRR. Time-resolved photoelectron imaging of the isolated deprotonated nucleotides. Chem Sci 2014. [DOI: 10.1039/c4sc01493f] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Time-resolved photoelectron spectroscopy of deprotonated nucleotides provides new insights into their relaxation dynamics.
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Affiliation(s)
- Adam S. Chatterley
- Department
- of Chemistry
- University of Durham
- Durham DH1 3LE, United Kingdom
- Department of Chemistry
| | | | - Vasilios G. Stavros
- Department of Chemistry
- University of Warwick
- Coventry CV4 7AL, United Kingdom
| | - Jan R. R. Verlet
- Department
- of Chemistry
- University of Durham
- Durham DH1 3LE, United Kingdom
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18
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Roberts GM, Stavros VG. The role of πσ* states in the photochemistry of heteroaromatic biomolecules and their subunits: insights from gas-phase femtosecond spectroscopy. Chem Sci 2014. [DOI: 10.1039/c3sc53175a] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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19
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Verlet JRR, Horke DA, Chatterley AS. Excited states of multiply-charged anions probed by photoelectron imaging: riding the repulsive Coulomb barrier. Phys Chem Chem Phys 2014; 16:15043-52. [DOI: 10.1039/c4cp01667j] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Recent progress towards understanding the repulsive Coulomb barrier in multiply-charged anion using photoelectron spectroscopy is discussed.
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Affiliation(s)
| | - Daniel A. Horke
- Center for Free-Electron Laser Science
- DESY
- 22607 Hamburg, Germany
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Staniforth M, Stavros VG. Recent advances in experimental techniques to probe fast excited-state dynamics in biological molecules in the gas phase: dynamics in nucleotides, amino acids and beyond. Proc Math Phys Eng Sci 2013; 469:20130458. [PMID: 24204191 PMCID: PMC3780818 DOI: 10.1098/rspa.2013.0458] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Accepted: 08/07/2013] [Indexed: 11/23/2022] Open
Abstract
In many chemical reactions, an activation barrier must be overcome before a chemical transformation can occur. As such, understanding the behaviour of molecules in energetically excited states is critical to understanding the chemical changes that these molecules undergo. Among the most prominent reactions for mankind to understand are chemical changes that occur in our own biological molecules. A notable example is the focus towards understanding the interaction of DNA with ultraviolet radiation and the subsequent chemical changes. However, the interaction of radiation with large biological structures is highly complex, and thus the photochemistry of these systems as a whole is poorly understood. Studying the gas-phase spectroscopy and ultrafast dynamics of the building blocks of these more complex biomolecules offers the tantalizing prospect of providing a scientifically intuitive bottom-up approach, beginning with the study of the subunits of large polymeric biomolecules and monitoring the evolution in photochemistry as the complexity of the molecules is increased. While highly attractive, one of the main challenges of this approach is in transferring large, and in many cases, thermally labile molecules into vacuum. This review discusses the recent advances in cutting-edge experimental methodologies, emerging as excellent candidates for progressing this bottom-up approach.
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Affiliation(s)
| | - Vasilios G. Stavros
- Department of Chemistry, University of Warwick, Library Road, Coventry CV4 7AL, UK
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