1
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Sajeev Y. Prebiotic chemical origin of biomolecular complementarity. Commun Chem 2023; 6:259. [PMID: 38012323 PMCID: PMC10681984 DOI: 10.1038/s42004-023-01060-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 11/10/2023] [Indexed: 11/29/2023] Open
Abstract
The early Earth, devoid of the protective stratospheric ozone layer, must have sustained an ambient prebiotic physicochemical medium intensified by the co-existence of shortwave UV photons and very low energy electrons (vLEEs). Consequently, only intrinsically stable molecules against these two co-existing molecular destructors must have proliferated and thereby chemically evolved into the advanced molecules of life. Based on this view, we examined the stability inherent in nucleobases and their complementary pairs as resistance to the molecular damaging effects of shortwave UV photons and vLEEs. This leads to the conclusion that nucleobases could only proliferated as their complementary pairs under the unfavorable prebiotic conditions on early Earth. The complementary base pairing not only enhances but consolidates the intrinsic stability of nucleobases against short-range UV photons, vLEEs, and possibly many as-yet-unknown deleterious agents co-existed in the prebiotic conditions of the early Earth. In short, complementary base pairing is a manifestation of chemical evolution in the unfavorable prebiotic medium created by the absence of the stratospheric ozone layer.
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Affiliation(s)
- Y Sajeev
- Theoretical Chemistry Section, Bhabha Atomic Research Centre, Mumbai, India.
- Homi Bhabha National Institute, Mumbai, India.
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2
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Narayanan S J J, Tripathi D, Verma P, Adhikary A, Dutta AK. Secondary Electron Attachment-Induced Radiation Damage to Genetic Materials. ACS OMEGA 2023; 8:10669-10689. [PMID: 37008102 PMCID: PMC10061531 DOI: 10.1021/acsomega.2c06776] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/23/2022] [Accepted: 02/20/2023] [Indexed: 06/19/2023]
Abstract
Reactions of radiation-produced secondary electrons (SEs) with biomacromolecules (e.g., DNA) are considered one of the primary causes of radiation-induced cell death. In this Review, we summarize the latest developments in the modeling of SE attachment-induced radiation damage. The initial attachment of electrons to genetic materials has traditionally been attributed to the temporary bound or resonance states. Recent studies have, however, indicated an alternative possibility with two steps. First, the dipole-bound states act as a doorway for electron capture. Subsequently, the electron gets transferred to the valence-bound state, in which the electron is localized on the nucleobase. The transfer from the dipole-bound to valence-bound state happens through a mixing of electronic and nuclear degrees of freedom. In the presence of aqueous media, the water-bound states act as the doorway state, which is similar to that of the presolvated electron. Electron transfer from the initial doorway state to the nucleobase-bound state in the presence of bulk aqueous media happens on an ultrafast time scale, and it can account for the decrease in DNA strand breaks in aqueous environments. Analyses of the theoretically obtained results along with experimental data have also been discussed.
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Affiliation(s)
- Jishnu Narayanan S J
- Department
of Chemistry, Indian Institute of Technology
Bombay, Powai, Mumbai 400076, India
| | - Divya Tripathi
- Department
of Chemistry, Indian Institute of Technology
Bombay, Powai, Mumbai 400076, India
| | - Pooja Verma
- Department
of Chemistry, Indian Institute of Technology
Bombay, Powai, Mumbai 400076, India
| | - Amitava Adhikary
- Department
of Chemistry, Oakland University, 146 Library Drive, Rochester, Michigan 48309, United States
| | - Achintya Kumar Dutta
- Department
of Chemistry, Indian Institute of Technology
Bombay, Powai, Mumbai 400076, India
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3
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Falkiewicz K, Kozak W, Zdrowowicz M, Spisz P, Chomicz-Mańka L, Torchala M, Rak J. Why 6-Iodouridine Cannot Be Used as a Radiosensitizer of DNA Damage? Computational and Experimental Studies. J Phys Chem B 2023; 127:2565-2574. [PMID: 36893332 PMCID: PMC10041638 DOI: 10.1021/acs.jpcb.3c00548] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/11/2023]
Abstract
Previous density functional theory (DFT) studies on 6-brominated pyrimidine nucleosides suggest that 6-iodo-2'-deoxyuridine (6IdU) should act as a better radiosensitizer than its 5-iodosubstituted 2'-deoxyuridine analogue. In this work, we show that 6IdU is unstable in an aqueous solution. Indeed, a complete disappearance of the 6IdU signal was observed during its isolation by reversed-phase high-performance liquid chromatography (RP-HPLC). As indicated by the thermodynamic characteristics for the SN1-type hydrolysis of 6IdU obtained at the CAM-B3LYP/DGDZVP++ level and the polarizable continuum model (PCM) of water, 6-iodouracil (6IU) was already released quantitatively at ambient temperatures. The simulation of the hydrolysis kinetics demonstrated that a thermodynamic equilibrium was reached within seconds for the title compound. To assess the reliability of the calculations carried out, we synthesized 6-iodouridine (6IUrd), which was, unlike 6IdU, sufficiently stable in an aqueous solution at room temperature. The activation barrier for the N-glycosidic bond dissociation in 6IUrd was estimated experimentally using an Arrhenius plot. The stabilities in water calculated for 6IdU, 6IUrd, and 5-iodo-2'-deoxyuridine (5IdU) could be explained by the electronic and steric effects of the 2'-hydroxy group present in the ribose moiety. Our studies highlight the issue of the hydrolytic stability of potentially radiosensitizing nucleotides which, besides having favorable dissociative electron attachment (DEA) characteristics, must be stable in water to have any practical application.
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Affiliation(s)
- Karina Falkiewicz
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Witold Kozak
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Magdalena Zdrowowicz
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Paulina Spisz
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
- Laboratory of Intermolecular Interactions, Department of Bioinorganic Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Lidia Chomicz-Mańka
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Mieczyslaw Torchala
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Janusz Rak
- Laboratory of Biological Sensitizers, Department of Physical Chemistry, Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
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4
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Storoniak P, Rak J, Wang H, Ko YJ, Bowen KH. Electrophilic Properties of 2'-Deoxyadenosine···Thymine Dimer: Photoelectron Spectroscopy and DFT Studies. J Phys Chem A 2021; 125:6591-6599. [PMID: 34310156 PMCID: PMC8389985 DOI: 10.1021/acs.jpca.1c03803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The anion radical of the 2'-deoxyadenosine···thymine (dAT•-) pair has been investigated experimentally and theoretically in the gas phase. By employing negative-ion photoelectron spectroscopy (PES), we have registered a spectrum typical for the valence-bound anion, featuring a broad peak at the electron-binding energy (EBE) between ∼1.5 and 2.2 eV with the maximum at ∼1.9 eV. The measured value of the adiabatic electron affinity (AEA) for dAT was estimated to be ∼1.1 eV. Calculations performed at the M06-2X/6-31++G(d,p) level revealed that the structure, where thymine is coordinated to the sugar of dA by two hydrogen bonds, is responsible for the observed PES signal. The AEAG and the vertical detachment energy of 0.91 and 1.68 eV, respectively, calculated for this structure reproduce the experimental values well. The role of the possible proton transfer in the stabilization of anionic radical complexes is discussed.
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Affiliation(s)
- Piotr Storoniak
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Janusz Rak
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, Gdańsk 80-308, Poland
| | - Haopeng Wang
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Yeon Jae Ko
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kit H Bowen
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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5
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Omar KA, Hasnaoui K, de la Lande A. First-Principles Simulations of Biological Molecules Subjected to Ionizing Radiation. Annu Rev Phys Chem 2021; 72:445-465. [PMID: 33878897 DOI: 10.1146/annurev-physchem-101419-013639] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ionizing rays cause damage to genomes, proteins, and signaling pathways that normally regulate cell activity, with harmful consequences such as accelerated aging, tumors, and cancers but also with beneficial effects in the context of radiotherapies. While the great pace of research in the twentieth century led to the identification of the molecular mechanisms for chemical lesions on the building blocks of biomacromolecules, the last two decades have brought renewed questions, for example, regarding the formation of clustered damage or the rich chemistry involving the secondary electrons produced by radiolysis. Radiation chemistry is now meeting attosecond science, providing extraordinary opportunities to unravel the very first stages of biological matter radiolysis. This review provides an overview of the recent progress made in this direction, focusing mainly on the atto- to femto- to picosecond timescales. We review promising applications of time-dependent density functional theory in this context.
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Affiliation(s)
- Karwan Ali Omar
- Institut de Chimie Physique, CNRS UMR 8000, Université Paris-Saclay, 91405 Orsay, France; .,Department of Chemistry, College of Education, University of Sulaimani, 41005 Kurdistan, Iraq
| | - Karim Hasnaoui
- High Performance Computing User Support Team, Institut du Développement et des Ressources en Informatique Scientifique (IDRIS), 91403 Orsay, France.,Maison de la Simulation, CNRS, Commissariat à l'Energie Atomique et aux Énergies Alternatives (CEA), Université Paris-Saclay, 91191 Gif-sur-Yvette, France
| | - Aurélien de la Lande
- Institut de Chimie Physique, CNRS UMR 8000, Université Paris-Saclay, 91405 Orsay, France;
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6
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Li S, Leeming MG, O'Hair RAJ. What are the Potential Sites of DNA Attack by N-Acetyl-p-benzoquinone Imine (NAPQI)? Aust J Chem 2020. [DOI: 10.1071/ch19361] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Metabolic bioactivation of small molecules can produce electrophilic metabolites that can covalently modify proteins and DNA. Paracetamol (APAP) is a commonly used over-the-counter analgesic, and its hepatotoxic side effects have been postulated to be due to the formation of the electrophilic metabolite N-acetylbenzoquinone imine (NAPQI). It has been established that NAPQI reacts to form covalent bonds to the side-chain functional groups of cysteine, methionine, tyrosine, and tryptophan residues. While there have been scattered reports that APAP can form adducts with DNA the nature of these adducts have not yet been fully characterised. Here the four deoxynucleosides, deoxyguanosine (dG), deoxyadenosine (dA), deoxycytidine (dC), and deoxythymidine (dT) were reacted with NAPQI and the formation of adducts was profiled using liquid chromatography–mass spectrometry with positive-ion mode electrospray ionisation and collision-induced dissociation. Covalent adducts were detected for dG, dA, and dC and tandem mass spectrometry (MS/MS) spectra revealed common neutral losses of deoxyribose (116 amu) arising from cleavage of the glyosidic bond with formation of the modified nucleobase. Of the four deoxynucleosides, dC proved to be the most reactive, followed by dG and dA. A pH dependence was found, with greater reactivity being observed at pH 5.5. The results of density functional theory calculations aimed at understanding the relative reactivities of the four deoxynucleosides towards NAPQI are described.
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7
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Khorsandgolchin G, Sanche L, Cloutier P, Wagner JR. Strand Breaks Induced by Very Low Energy Electrons: Product Analysis and Mechanistic Insight into the Reaction with TpT. J Am Chem Soc 2019; 141:10315-10323. [PMID: 31244176 DOI: 10.1021/jacs.9b03295] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Numerous experimental studies show that 5-15 eV electrons induce strand breaks in DNA at energies below the ionization threshold of DNA components. In this energy range, DNA damage arises principally by the formation of transient negative ions, decaying into dissociative electron attachment (DEA) and electronic excitation of dissociative states. Here, we carried out LC-MS/MS analysis of the degradation products arising from bombardment of TpT, a DNA model compound, irradiated with very low energy electrons (vLEEs; ∼1.8 eV). The formation of thymidine 5'-monophosphate (TMP5') together with 2',3'-dideoxythymidine (ddT3') can be explained by cleavage of the C3'-O bond of TpT, whereas thymidine 3'-monophosphate (TMP3') and 2',5'-dideoxythymidine (ddT5') are formed by cleavage of the C5'-O bond. The formation of ddT3' and ddT5' decreased upon irradiation of either TMP5' or TMP3', and even further in the case of thymidine, underlining the critical role of the phosphate group. Interestingly, the yield of TMP5' and TMP3' was higher than that of the corresponding ddT3' and ddT5' products, suggesting alternative fates of C3' and C5'-centered sugar radicals. In contrast, the release of thymine from TpT was minor (<20%) and did not result in the formation of expected products from DEA-mediated cleavage at the N-glycosidic bond. Lastly, vLEE induced the conversion of thymine to 5,6-dihydrothymine (5,6-dhT) within TpT, a reaction likely involving thymine anion radicals. In summary, we show that a major pathway of vLEEs involves DEA-mediated cleavage of the C3'-O and C5'-O bonds of TpT, resulting in the formation of specific fragments, which represent a prompt single strand break in DNA.
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Affiliation(s)
- Ghazal Khorsandgolchin
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences , Université de Sherbrooke , Sherbrooke , Quebec J1H 5N4 , Canada
| | - Léon Sanche
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences , Université de Sherbrooke , Sherbrooke , Quebec J1H 5N4 , Canada
| | - Pierre Cloutier
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences , Université de Sherbrooke , Sherbrooke , Quebec J1H 5N4 , Canada
| | - J Richard Wagner
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences , Université de Sherbrooke , Sherbrooke , Quebec J1H 5N4 , Canada
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8
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Meißner R, Makurat S, Kozak W, Limão-Vieira P, Rak J, Denifl S. Electron-Induced Dissociation of the Potential Radiosensitizer 5-Selenocyanato-2'-deoxyuridine. J Phys Chem B 2019; 123:1274-1282. [PMID: 30657689 DOI: 10.1021/acs.jpcb.8b11523] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
5-Selenocyanato-2'-deoxyuridine (SeCNdU) is a recently proposed radiosensitizer based on 2'-deoxyuridine (dU) with the electron-affinic selenocyanato (-SeCN) side group attached at the C5 position of uracil. Since electron interaction processes may be an important source of DNA damage by ionizing radiation, we have studied low-energy dissociative electron attachment to SeCNdU in the gas phase. Negative ion formation has been obtained by means of mass spectrometry, where a rich fragmentation pattern is observed even at ∼0 eV. The reaction pathways exhibiting the highest ion yields are C4N2O2H2Se•- and CN-, both involving a cleavage of the Se-CN bond. The heaviest fragment anion observed is C9N2O5H10Se•-, where besides the charged species, the hydrogen and cyano radicals are also formed. Further decomposition channels also yield the highly reactive hydroxyl radical, which possesses a high DNA damage potential. All observed channels have experimentally determined onsets at 0 eV, which are supported by calculations performed at the M06-2X/aug-cc-pVTZ level. The calculations comprise the thermochemical thresholds at standard and experimental (428.15 K, 3 × 10-11 atm) conditions together with the adiabatic electron affinities. The present study shows that low-energy electrons very effectively decompose SeCNdU upon attachment of thermal electrons, producing a large variety of charged fragments and radicals.
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Affiliation(s)
- Rebecca Meißner
- Institut für Ionenphysik und Angewandte Physik and Center for Biomolecular Sciences Innsbruck , Leopold-Franzens Universität Innsbruck , Technikerstrasse 25 , A-6020 Innsbruck , Austria.,Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics , Universidade NOVA de Lisboa , 2829-516 Caparica , Portugal
| | - Samanta Makurat
- Laboratory of Biological Sensitizers, Physical Chemistry Department, Faculty of Chemistry , University of Gdańsk , 80-308 Gdańsk , Poland
| | - Witold Kozak
- Laboratory of Biological Sensitizers, Physical Chemistry Department, Faculty of Chemistry , University of Gdańsk , 80-308 Gdańsk , Poland
| | - Paulo Limão-Vieira
- Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics , Universidade NOVA de Lisboa , 2829-516 Caparica , Portugal
| | - Janusz Rak
- Laboratory of Biological Sensitizers, Physical Chemistry Department, Faculty of Chemistry , University of Gdańsk , 80-308 Gdańsk , Poland
| | - Stephan Denifl
- Institut für Ionenphysik und Angewandte Physik and Center for Biomolecular Sciences Innsbruck , Leopold-Franzens Universität Innsbruck , Technikerstrasse 25 , A-6020 Innsbruck , Austria
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9
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Zhang Y, Wang J, Yang S. Notable effect of water on excess electron attachment to aqueous DNA deoxyribonucleosides. Phys Chem Chem Phys 2019; 21:8925-8932. [DOI: 10.1039/c9cp00536f] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
As excess electrons are vertically attached to aqueous deoxyribonucleosides, ∼50% of excess electrons would be delocalized over the water molecules.
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Affiliation(s)
- Yan Zhang
- Institute of Molecular Sciences and Engineering
- Shandong University, Qingdao
- Qingdao 266237
- China
| | - Jiayue Wang
- State Key Laboratory of Molecular Reaction Dynamics
- Dalian Institute of Chemical Physics
- Chinese Academy of Science
- Dalian 116023
- China
| | - Songqiu Yang
- State Key Laboratory of Molecular Reaction Dynamics
- Dalian Institute of Chemical Physics
- Chinese Academy of Science
- Dalian 116023
- China
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10
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Choofong S, Cloutier P, Sanche L, Wagner JR. Base Release and Modification in Solid-Phase DNA Exposed to Low-Energy Electrons. Radiat Res 2016; 186:520-530. [PMID: 27802110 DOI: 10.1667/rr14476.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Ionization generates a large number of secondary low-energy electrons (LEEs) with a most probable energy of approximately 10 eV, which can break DNA bonds by dissociative electron attachment (DEA) and lead to DNA damage. In this study, we investigated radiation damage to dry DNA induced by X rays (1.5 keV) alone on a glass substrate or X rays combined with extra LEEs (average energy of 5.8 eV) emitted from a tantalum (Ta) substrate under an atmosphere of N2 and standard ambient conditions of temperature and pressure. The targets included calf-thymus DNA and double-stranded synthetic oligonucleotides. We developed analytical methods to measure the release of non-modified DNA bases from DNA and the formation of several base modifications by LC-MS/MS with isotopic dilution for precise quantification. The results show that the yield of non-modified bases as well as base modifications increase by 20-30% when DNA is deposited on a Ta substrate compared to that on a glass substrate. The order of base release (Gua > Ade > Thy ∼ Cyt) agrees well with several theoretical studies indicating that Gua is the most susceptible site toward sugar-phosphate cleavage. The formation of DNA damage by LEEs is explained by DEA leading to the release of non-modified bases involving the initial cleavage of N1-C1', C3'-O3' or C5'-O5' bonds. The yield of base modifications was lower than the release of non-modified bases. The main LEE-induced base modifications include 5,6-dihydrothymine (5,6-dHT), 5,6-dihydrouracil (5-dHU), 5-hydroxymethyluracil (5-HmU) and 5-formyluracil (5-ForU). The formation of base modifications by LEEs can be explained by DEA and cleavage of the C-H bond of the methyl group of Thy (giving 5-HmU and 5-ForU) and by secondary reactions of H atoms and hydride anions that are generated by primary LEE reactions followed by subsequent reaction with Cyt and Thy (giving 5,6-dHU and 5,6-dHT).
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Affiliation(s)
- Surakarn Choofong
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Pierre Cloutier
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Léon Sanche
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - J Richard Wagner
- Department of Nuclear Medicine and Radiobiology, Faculty of Medicine and Health Sciences, Université de Sherbrooke, Sherbrooke, Quebec, Canada
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11
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Ling S, Gutowski M. Different Conformations of 2′-Deoxycytidine in the Gas and Solid Phases: Competition between Intra- and Intermolecular Hydrogen Bonds. J Phys Chem A 2016; 120:8199-8210. [DOI: 10.1021/acs.jpca.6b09384] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Sanliang Ling
- Institute
of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
- Department
of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Maciej Gutowski
- Institute
of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom
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12
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Storoniak P, Rak J, Ko YJ, Wang H, Bowen KH. Excess Electron Attachment to the Nucleoside Pair 2′-Deoxyadenosine (dA)–2′-Deoxythymidine (dT). J Phys Chem B 2016; 120:4955-62. [DOI: 10.1021/acs.jpcb.6b03450] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Piotr Storoniak
- Faculty
of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Janusz Rak
- Faculty
of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland
| | - Yeon Jae Ko
- Department
of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Haopeng Wang
- Department
of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kit H. Bowen
- Department
of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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13
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Wang S, Zhao P, Zhang C, Bu Y. The Equally Important Role of Adenine Derivatives to That of Pyrimidine Derivatives in Near‐0 eV Electron‐Induced DNA Lesions. Chemphyschem 2016; 17:1669-77. [DOI: 10.1002/cphc.201600002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2016] [Indexed: 01/27/2023]
Affiliation(s)
- Shoushan Wang
- Institute of Theoretical Chemistry School of Chemistry and Chemical Engineering Shandong University Jinan 250100 P. R. China
| | - Peiwen Zhao
- Institute of Theoretical Chemistry School of Chemistry and Chemical Engineering Shandong University Jinan 250100 P. R. China
| | - Changzhe Zhang
- Institute of Theoretical Chemistry School of Chemistry and Chemical Engineering Shandong University Jinan 250100 P. R. China
| | - Yuxiang Bu
- Institute of Theoretical Chemistry School of Chemistry and Chemical Engineering Shandong University Jinan 250100 P. R. China
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14
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Bhaskaran R, Sarma M. Low energy electron induced cytosine base release in 2'-deoxycytidine-3'-monophosphate via glycosidic bond cleavage: a time-dependent wavepacket study. J Chem Phys 2015; 141:104309. [PMID: 25217918 DOI: 10.1063/1.4894744] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Low energy electron (LEE) induced cytosine base release in a selected pyrimidine nucleotide, viz., 2'-deoxycytidine-3'-monophosphate is investigated using ab initio electronic structure methods and time dependent quantum mechanical calculations. It has been noted that the cytosine base scission is comparatively difficult process than the 3' C-O bond cleavage from the lowest π* shape resonance in energy region <1 eV. This is mainly due to the high activation energy barrier associated with the electron transfer from the π* orbital of the base to the σ* orbital of the glycosidic N-C bond. In addition, the metastable state formed after impinging LEE (0-1 eV) has very short lifetime (10 fs) which may decay in either of the two competing auto-detachment or dissociation process simultaneously. On the other hand, the selected N-C mode may cleave to form the cytosine base anion at higher energy regions (>2 eV) via tunneling of the glycosidic bond. Resonance states generated within this energy regime will exist for a duration of ~35-55 fs. Comparison of salient features of the two dissociation events, i.e., 3' C-O single strand break and glycosidic N-C bond cleavage in 3'-dCMPH molecule are also provided.
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Affiliation(s)
- Renjith Bhaskaran
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781 039, India
| | - Manabendra Sarma
- Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781 039, India
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15
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Chen Z, Zeng B, Tao J, Kang Y, Xue Y. A theoretical exploration of the photoinduced reductive repair mechanisms of thymidine glycol. J Photochem Photobiol A Chem 2014. [DOI: 10.1016/j.jphotochem.2014.08.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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16
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Chen HY, Yang PY, Chen HF, Kao CL, Liao LW. DFT reinvestigation of DNA strand breaks induced by electron attachment. J Phys Chem B 2014; 118:11137-44. [PMID: 25184499 DOI: 10.1021/jp506679b] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The benchmark study of DFT methods on the activation energies of phosphodiester C3'-O and C5'-O bond ruptures and glycosidic C1'-N bond ruptures induced by electron attachment was performed. While conventional pure and hybrid functionals provide a relatively reasonable description for the C1'-N bond rupture, they significantly underestimate the energy barriers of the C-O bond ruptures. This is because the transition states of the later reactions, which are characterized by an electron distribution delocalized from the nucleobase to sugar-phosphate backbone, suffer from a severe self-interaction error in common DFT methods. CAM-B3LYP, M06-2X, and ωB97XD are the top three methods that emerged from the benchmark study; the mean absolute errors relative to the CCSD(T) values are 1.7, 1.9, and 2.2 kcal/mol, respectively. The C-O bond cleavages of 3'- and 5'-dXMP(•-), where X represents four nucleobases, were then recalculated at the M06-2X/6-31++G**//M06-2X/6-31+G* level, and it turned out that the C-O bond cleavages do not proceed as easily as previously predicted by the B3LYP calculations. Our calculations revealed that the C-O bonds of purine nucleotides are more susceptible than pyrimidine nucleotides to the electron attachment. The energies of electron attachment to nucleotides were calculated and discussed as well.
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Affiliation(s)
- Hsing-Yin Chen
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University , Kaohsiung 807, Taiwan
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17
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Golon Ł, Chomicz L, Rak J. Electron-induced single strand break in the nucleotide of 5- and 6-bromouridine. A DFT study. Chem Phys Lett 2014. [DOI: 10.1016/j.cplett.2014.08.049] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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18
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Alizadeh E, Sanz AG, Madugundu GS, García G, Wagner JR, Sanche L. Thymidine Decomposition Induced by Low-Energy Electrons and Soft X Rays under N2and O2Atmospheres. Radiat Res 2014; 181:629-40. [DOI: 10.1667/rr13584.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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19
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Gu J, Wang J, Leszczynski J. Electron interaction with phosphate cytidine oligomer dCpdC: base-centered radical anions and their electronic spectra. J Phys Chem B 2014; 118:915-20. [PMID: 24397482 DOI: 10.1021/jp409247d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Computational chemistry approach was applied to explore the nature of electron attachment to cytosine-rich DNA single strands. An oligomer dinucleoside phosphate deoxycytidylyl-3',5'-deoxycytidine (dCpdC) was selected as a model system for investigations by density functional theory. Electron distribution patterns for the radical anions of dCpdC in aqueous solution were explored. The excess electron may reside on the nucleobase at the 5' position (dC(•-)pdC) or at the 3' position (dCpdC(•-)). From comparison with electron attachment to the cytosine related DNA fragments, the electron affinity for the formation of the cytosine-centered radical anion in DNA is estimated to be around 2.2 eV. Electron attachment to cytosine sites in DNA single strands might cause perturbations of local structural characteristics. Visible absorption spectroscopy may be applied to validate computational results and determine experimentally the existence of the base-centered radical anion. The time-dependent DFT study shows the absorption around 550-600 nm for the cytosine-centered radical anions of DNA oligomers. This indicates that if such species are detected experimentally they would be characterized by a distinctive color.
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Affiliation(s)
- Jiande Gu
- Drug Design & Discovery Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences , Shanghai 201203 China
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20
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Storoniak P, Rak J, Ko YJ, Wang H, Bowen KH. Photoelectron spectroscopic and density functional theoretical studies of the 2′-deoxycytidine homodimer radical anion. J Chem Phys 2013; 139:075101. [DOI: 10.1063/1.4817779] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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21
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Cauët E, Bogatko S, Liévin J, De Proft F, Geerlings P. Electron-Attachment-Induced DNA Damage: Instantaneous Strand Breaks. J Phys Chem B 2013; 117:9669-76. [DOI: 10.1021/jp406320g] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Emilie Cauët
- General Chemistry - Algemene
Chemie, Vrije Universiteit Brussel, Pleinlaan
2, B-1050 Brussels, Belgium
- Service de Chimie Quantique
et Photophysique, Université Libre de Bruxelles, Avenue F.D. Roosevelt 50, CPi160/09, B-1050 Brussels, Belgium
| | - Stuart Bogatko
- General Chemistry - Algemene
Chemie, Vrije Universiteit Brussel, Pleinlaan
2, B-1050 Brussels, Belgium
| | - Jacques Liévin
- Service de Chimie Quantique
et Photophysique, Université Libre de Bruxelles, Avenue F.D. Roosevelt 50, CPi160/09, B-1050 Brussels, Belgium
| | - Frank De Proft
- General Chemistry - Algemene
Chemie, Vrije Universiteit Brussel, Pleinlaan
2, B-1050 Brussels, Belgium
| | - Paul Geerlings
- General Chemistry - Algemene
Chemie, Vrije Universiteit Brussel, Pleinlaan
2, B-1050 Brussels, Belgium
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22
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Ko YJ, Storoniak P, Wang H, Bowen KH, Rak J. Photoelectron spectroscopy and density functional theory studies on the uridine homodimer radical anions. J Chem Phys 2012. [PMID: 23206036 DOI: 10.1063/1.4767053] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
We report the photoelectron spectrum (PES) of the homogeneous dimer anion radical of uridine, (rU)(2)(●-). It features a broad band consisting of an onset of ∼1.2 eV and a maximum at the electron binding energy (EBE) ranging from 2.0 to 2.5 eV. Calculations performed at the B3LYP∕6-31++G∗∗ level of theory suggest that the PES is dominated by dimeric radical anions in which one uridine nucleoside, hosting the excess charge on the base moiety, forms hydrogen bonds via its O8 atom with hydroxyl of the other neutral nucleoside's ribose. The calculated adiabatic electron affinities (AEAGs) and vertical detachment energies (VDEs) of the most stable homodimers show an excellent agreement with the experimental values. The anionic complexes consisting of two intermolecular uracil-uracil hydrogen bonds appeared to be substantially less stable than the uracil-ribose dimers. Despite the fact that uracil-uracil anionic homodimers are additionally stabilized by barrier-free electron-induced proton transfer, their relative thermodynamic stabilities and the calculated VDEs suggest that they do not contribute to the experimental PES spectrum of (rU)(2)(●-).
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Affiliation(s)
- Yeon Jae Ko
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
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23
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Gu J, Leszczynski J, Schaefer HF. Interactions of electrons with bare and hydrated biomolecules: from nucleic acid bases to DNA segments. Chem Rev 2012; 112:5603-40. [PMID: 22694487 DOI: 10.1021/cr3000219] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Jiande Gu
- Drug Design & Discovery Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, CAS, PR China.
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24
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Gu J, Wang J, Leszczynski J. Low Energy Electron Attachment to the Adenosine Site of DNA. J Phys Chem B 2011; 115:14831-7. [DOI: 10.1021/jp207801e] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jiande Gu
- Drug Design & Discovery Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, CAS Shanghai, 201203 P. R. China
- Interdisciplinary Nanotoxicity Center, Department of Chemistry and Biochemistry, Jackson State University, Jackson, Mississippi 39217, United States
| | - Jing Wang
- Interdisciplinary Nanotoxicity Center, Department of Chemistry and Biochemistry, Jackson State University, Jackson, Mississippi 39217, United States
| | - Jerzy Leszczynski
- Interdisciplinary Nanotoxicity Center, Department of Chemistry and Biochemistry, Jackson State University, Jackson, Mississippi 39217, United States
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25
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Li X, Wang H, Bowen KH. Photoelectron spectroscopic study of the hydrated nucleoside anions: Uridine−(H2O)n=0–2, cytidine−(H2O)n=0–2, and thymidine−(H2O)n=0,1. J Chem Phys 2010; 133:144304. [DOI: 10.1063/1.3487735] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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26
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Storoniak P, Mazurkiewicz K, Haranczyk M, Gutowski M, Rak J, Eustis SN, Ko YJ, Wang H, Bowen KH. The Anionic (9-Methyladenine)−(1-Methylthymine) Base Pair Solvated by Formic Acid. A Computational and Photoelectron Spectroscopy Study. J Phys Chem B 2010; 114:11353-62. [DOI: 10.1021/jp104668h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Affiliation(s)
- Piotr Storoniak
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mail Stop 50F-1650, Berkeley, California 94720-8139, Chemistry-School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K., and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Kamil Mazurkiewicz
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mail Stop 50F-1650, Berkeley, California 94720-8139, Chemistry-School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K., and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Maciej Haranczyk
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mail Stop 50F-1650, Berkeley, California 94720-8139, Chemistry-School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K., and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Maciej Gutowski
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mail Stop 50F-1650, Berkeley, California 94720-8139, Chemistry-School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K., and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Janusz Rak
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mail Stop 50F-1650, Berkeley, California 94720-8139, Chemistry-School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K., and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Soren N. Eustis
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mail Stop 50F-1650, Berkeley, California 94720-8139, Chemistry-School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K., and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Yeon Jae Ko
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mail Stop 50F-1650, Berkeley, California 94720-8139, Chemistry-School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K., and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Haopeng Wang
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mail Stop 50F-1650, Berkeley, California 94720-8139, Chemistry-School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K., and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Kit H. Bowen
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Computational Research Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Mail Stop 50F-1650, Berkeley, California 94720-8139, Chemistry-School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K., and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
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27
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Li Z, Cloutier P, Sanche L, Wagner JR. Low-energy electron-induced DNA damage: effect of base sequence in oligonucleotide trimers. J Am Chem Soc 2010; 132:5422-7. [PMID: 20345139 DOI: 10.1021/ja9099505] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
DNA damage induced by low-energy electrons (LEEs) has attracted considerable attention in recent years because LEEs represent a large percentage of the total energy deposited by ionizing radiation and because LEEs have been shown to damage DNA components. In this article, we have studied the effect of base sequences in a series of oligonucleotide trimers by the analysis of damage remaining within the nonvolatile condensed phase after LEE irradiation. The model compounds include TXT, where X represents one of the four normal bases of DNA (thymine (T), cytosine (C), adenine (A), and guanine (G)). Using HPLC-UV analysis, several known fragments were quantified from the release of nonmodified nucleobases (T and X) as well as from phosphodiester C-O bond cleavage (pT, pXT, Tp, and TXp). The total damage was estimated by the disappearance of the parent peaks in the chromatogram of nonirradiated and irradiated samples. When trimers were irradiated with LEE (10 eV), the total damage decreased 2-fold in the following order: TTT > TCT > TAT > TGT. The release of nonmodified nuclobases (giving from 17 to 24% of the total products) mainly occurred from the terminal sites of trimers (i.e., T) whereas the release of central nucleobases was minor (C) or not at all detected (A and G). In comparison, the formation of products arising from phosphodiester bond cleavage accounted for 9 to 20% of the total damage and it partitioned to the four possible sites of cleavage present in trimers. This study indicates that the initial LEE capture and subsequent bond breaking within the intermediate anion depend on the sequence and electron affinity of the bases, with the most damage attributed to the most electronegative base, T.
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Affiliation(s)
- Zejun Li
- Center for Radiobiology and Radiotherapy, Department of Nuclear Medicine and Radiobiology, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4
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Gu J, Wang J, Leszczynski J. Electron attachment-induced DNA single-strand breaks at the pyrimidine sites. Nucleic Acids Res 2010; 38:5280-90. [PMID: 20430827 PMCID: PMC2938206 DOI: 10.1093/nar/gkq304] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
To elucidate the contribution of pyrimidine in DNA strand breaks caused by low-energy electrons (LEEs), theoretical investigations of the LEE attachment-induced C3′–O3′, and C5′–O5′ σ bond as well as N-glycosidic bond breaking of 2′-deoxycytidine-3′,5′-diphosphate and 2′-deoxythymidine-3′,5′-diphosphate were performed using the B3LYP/DZP++ approach. The base-centered radical anions are electronically stable enough to assure that either the C–O or glycosidic bond breaking processes might compete with the electron detachment and yield corresponding radical fragments and anions. In the gas phase, the computed glycosidic bond breaking activation energy (24.1 kcal/mol) excludes the base release pathway. The low-energy barrier for the C3′–O3′ σ bond cleavage process (∼6.0 kcal/mol for both cytidine and thymidine) suggests that this reaction pathway is the most favorable one as compared to other possible pathways. On the other hand, the relatively low activation energy barrier (∼14 kcal/mol) for the C5′–O5′ σ bond cleavage process indicates that this bond breaking pathway could be possible, especially when the incident electrons have relatively high energy (a few electronvolts). The presence of the polarizable medium greatly increases the activation energies of either C–O σ bond cleavage processes or the N-glycosidic bond breaking process. The only possible pathway that dominates the LEE-induced DNA single strands in the presence of the polarizable surroundings (such as in an aqueous solution) is the C3′–O3′ σ bond cleavage (the relatively low activation energy barrier, ∼13.4 kcal/mol, has been predicted through a polarizable continuum model investigation). The qualitative agreement between the ratio for the bond breaks of C5′–O5′, C3′–O3′ and N-glycosidic bonds observed in the experiment of oligonucleotide tetramer CGAT and the theoretical sequence of the bond breaking reaction pathways have been found. This consistency between the theoretical predictions and the experimental observations provides strong supportive evidences for the base-centered radical anion mechanism of the LEE-induced single-strand bond breaking around the pyrimidine sites of the DNA single strands.
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Affiliation(s)
- Jiande Gu
- Drug Design & Discovery Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, CAS, Shanghai 201203 PR China.
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29
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Szyperska A, Rak J, Leszczynski J, Li X, Ko YJ, Wang H, Bowen KH. Low-Energy-Barrier Proton Transfer Induced by Electron Attachment to the Guanine⋅⋅⋅Cytosine Base Pair. Chemphyschem 2010; 11:880-8. [DOI: 10.1002/cphc.200900810] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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30
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Gu J, Wang J, Leszczynski J. Comprehensive Analysis of DNA Strand Breaks at the Guanosine Site Induced by Low-Energy Electron Attachment. Chemphyschem 2010; 11:175-81. [DOI: 10.1002/cphc.200900656] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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31
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Kobyłecka M, Leszczynski J, Rak J. Stability of the valence anion of cytosine is governed by nucleobases sequence in the double stranded DNA pi-stack: A computational study. J Chem Phys 2009; 131:085103. [PMID: 19725636 DOI: 10.1063/1.3204939] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The stabilities of the valence anion of cytosine (C(-)) in model trimers of complementary base pairs that possess the B-DNA geometry but differ in base sequence are reported. In order to estimate the energetics of electron attachment to the middle cytosine incorporated in the trimer, a thermodynamic cycle employing all possible two-body interaction energies in the neutral and anionic duplex as well as the adiabatic electron affinity of isolated cytosine were developed. All calculations were carried out at the MP2 level of theory with the aug-cc-pVDZ basis set. We have demonstrated that contrary to the literature reports, concerning single stranded DNA, the sequence of nucleic bases has a profound effect on the stability of the cytosine valence anion. The anionic 3(')-CCC-5(') complex is the most stable configuration (EA=0.399 eV) and the 3(')-GCG-5(') trimer anion is the most unstable species (EA=-0.193 eV). Moreover, with the energetic correction for the presence of sugar-phosphate backbone all possible double stranded DNA sequences lead to the stable C(-). The predicted electron affinities of the cytosine anion have been compared to the results of analogous studies on the thymine anion published recently [M. Kobyłecka et al., J. Am. Chem. Soc. 130, 15683 (2008)]. The consequences of low-energy barrier proton transfer in the GC anion have been discussed in the context of induced by electrons DNA single strand breaks. The DNA sequences that should dramatically differ in their vulnerability to be damaged by low energy electrons have been proposed.
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Affiliation(s)
- Monika Kobyłecka
- Faculty of Chemistry, University of Gdańsk, 80-952 Gdansk, Poland
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32
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Sharma KK, Razskazovskiy Y, Purkayastha S, Bernhard WA. Mechanisms of strand break formation in DNA due to the direct effect of ionizing radiation: the dependency of free base release on the length of alternating CG oligodeoxynucleotides. J Phys Chem B 2009; 113:8183-91. [PMID: 19492855 DOI: 10.1021/jp900803b] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The question of how NA base sequence influences the yield of DNA strand breaks produced by the direct effect of ionizing radiation was investigated in a series of oligodeoxynucleotides of the form (d(CG)(n))(2) and (d(GC)(n))(2). The yields of free base release from X-irradiated DNA films containing 2.5 waters/nucleotide were measured by HPLC as a function of oligomer length. For (d(CG)(n))(2), the ratio of the Gua yield to Cyt yield, R, was relatively constant at 2.4-2.5 for n = 2-4 and it decreased to 1.2 as n increased from 5 to 10. When Gua was moved to the 5' end, for example going from d(CG)(5) to d(GC)(5), R dropped from 1.9 +/- 0.1 to 1.1 +/- 0.1. These effects are poorly described if the chemistry at the oligomer ends is assumed to be independent of the remainder of the oligomer. A mathematical model incorporating charge transfer through the base stack was derived to explain these effects. In addition, EPR was used to measure the yield of trapped-deoxyribose radicals at 4 K following X-irradiation at 4 K. The yield of free base release was substantially greater, by 50-100 nmol/J, than the yield of trapped-deoxyribose radicals. Therefore, a large fraction of free base release stems from a nonradical intermediate. For this intermediate, a deoxyribose carbocation formed by two one-electron oxidations is proposed. This reaction pathway requires that the hole (electron loss site) transfers through the base stack and, upon encountering a deoxyribose hole, oxidizes that site to form a deoxyribose carbocation. This reaction mechanism provides a consistent way of explaining both the absence of trapped radical intermediates and the unusual dependence of free base release on oligomer length.
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Affiliation(s)
- Kiran K Sharma
- Department of Biochemistry, University of Rochester Medical Center, Rochester, New York 14642, USA
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Szyperska A, Rak J, Leszczynski J, Li X, Ko YJ, Wang H, Bowen KH. Valence Anions of 9-Methylguanine−1-Methylcytosine Complexes. Computational and Photoelectron Spectroscopy Studies. J Am Chem Soc 2009; 131:2663-9. [DOI: 10.1021/ja808313e] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- Anna Szyperska
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Interdisciplinary Nanotoxicity Center, Department of Chemistry, Jackson State University, Jackson, Mississippi 39217, and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Janusz Rak
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Interdisciplinary Nanotoxicity Center, Department of Chemistry, Jackson State University, Jackson, Mississippi 39217, and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Jerzy Leszczynski
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Interdisciplinary Nanotoxicity Center, Department of Chemistry, Jackson State University, Jackson, Mississippi 39217, and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Xiang Li
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Interdisciplinary Nanotoxicity Center, Department of Chemistry, Jackson State University, Jackson, Mississippi 39217, and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Yeon Jae Ko
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Interdisciplinary Nanotoxicity Center, Department of Chemistry, Jackson State University, Jackson, Mississippi 39217, and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Haopeng Wang
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Interdisciplinary Nanotoxicity Center, Department of Chemistry, Jackson State University, Jackson, Mississippi 39217, and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
| | - Kit H. Bowen
- Department of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952 Gdańsk, Poland, Interdisciplinary Nanotoxicity Center, Department of Chemistry, Jackson State University, Jackson, Mississippi 39217, and Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218
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Liang G, Bao X, Gu J. The possibility of the decomposition of 2′-deoxyribose moiety of thymidine induced by the low energy electron attachment. J Comput Chem 2008; 29:2648-55. [DOI: 10.1002/jcc.21009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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35
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Xie H, Wu R, Xia F, Cao Z. Effects of electron attachment on C5'-O5' and C1'-N1 bond cleavages of pyrimidine nucleotides: A theoretical study. J Comput Chem 2008; 29:2025-32. [PMID: 18432616 DOI: 10.1002/jcc.20967] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Sugar-base C(1')-N(1) and phosphate-sugar C(5')-O(5') bond breakings of 2'-deoxycytidine-5'-monophosphates (dCMP) and 2'-deoxythymidine-5'- monophosphates (dTMP) and their radical anions have been explored theoretically at the B3LYP/DZP++ level of theory. Calculations show that the low-energy electrons attachment to the pyrimidine nucleotides results in remarkable structural and chemical bonding changes. Predicted Gibbs free energies of reaction DeltaG for the C(5')-O(5') bond dissociation process of the radical anions are -14.6 and -11.5 kcal mol(-1), respectively, and such dissociation processes may be intrinsically spontaneous in the gas phase. Furthermore, the C(5')-O(5') bond cleavage processes of the anionic dCMP and dTMP were predicted to have activation energies of 6.9 and 8.0 kcal mol(-1) in the gas phase, respectively, much lower than the barriers for the C(1')-N(1) bond breaking process, showing that the C-O bond dissociation in DNA single strand breaks is a dominant process as observed experimentally.
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Affiliation(s)
- Hujun Xie
- Department of Chemistry and State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
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36
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Phosphodiester bond rupture in 5′ and 3′ cytosine monophosphate in aqueous environment and the effect of low-energy electron attachment: A Car–Parrinello QM/MM molecular dynamics study. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.07.106] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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37
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Zhang JD, Chen Z, Schaefer HF. Electron attachment to the hydrogenated Watson-Crick guanine cytosine base pair (GC+H): conventional and proton-transferred structures. J Phys Chem A 2008; 112:6217-26. [PMID: 18557604 DOI: 10.1021/jp711958p] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The anionic species resulting from hydride addition to the Watson-Crick guanine-cytosine (GC) DNA base pair are investigated theoretically. Proton-transferred structures of GC hydride, in which proton H1 of guanine or proton H4 of cytosine migrates to the complementary base-pair side, have been studied also. All optimized geometrical structures are confirmed to be minima via vibrational frequency analyses. The lowest energy structure places the additional hydride on the C6 position of cytosine coupled with proton transfer, resulting in the closed-shell anion designated 1T (G(-)C(C6)). Energetically, the major groove side of the GC pair has a greater propensity toward hydride/hydrogen addition than does the minor grove side. The pairing (dissociation) energy and electron-attracting ability of each anionic structure are predicted and compared with those of the neutral GC and the hydrogenated GC base pairs. Anion 8T (G(O6)C(-)) is a water-extracting complex and has the largest dissociation energy. Anion 2 (GC(C4)(-)) and the corresponding open-shell radical GC(C4) have the largest vertical electron detachment energy and adiabatic electron affinity, respectively. From the difference between the dissociation energy and electron-removal ability of the normal GC anion and the most favorable structure of GC hydride, it is clear that one may dissociate the GC anion and maintain the integrity of the GC hydride.
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Affiliation(s)
- J David Zhang
- Center for Computational Chemistry and Department of Chemistry, University of Georgia, Athens, GA 30602-2525, USA
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38
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Zhang RB, Zhang K, Eriksson LA. Theoretical studies of damage to 3'-uridine monophosphate induced by electron attachment. Chemistry 2008; 14:2850-6. [PMID: 18213558 DOI: 10.1002/chem.200701324] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Low-energy electrons (LEE) are well known to induce nucleic acid damage. However, the damage mechanisms related to charge state and structural features remain to be explored in detail. In the present work, we have investigated the N1-glycosidic and C3'-O(P) bond ruptures of 3'-UMP (UMP=uridine monophosphate) and the protonated form 3'-UMPH with -1 and zero charge, respectively, based on hybrid density functional theory (DFT) B3 LYP together with the 6-31+G(d,p) basis set. The glycosidic bond breakage reactions of the 3'UMP and 3'UMPH electron adducts are exothermic in both cases, with barrier heights of 19-20 kcal mol(-1) upon inclusion of bulk solvation. The effects of the charge state on the phosphate group are marginal, but the C2'-OH group destabilizes the transition structure of glycosidic bond rupture of 3'-UMPH in the gas phase by approximately 5.0 kcal mol(-1). This is in contrast with the C3'-O(P) bond ruptures induced by LEE in which the charge state on the phosphate influences the barrier heights and reaction energies considerably. The barrier towards C3'-O(P) bond dissociation in the 3'UMP electron adduct is higher in the gas phase than the one corresponding to glycosidic bond rupture and is dramatically influenced by the C2'-OH group and bulk salvation, which decreases the barrier to 14.7 kcal mol(-1). For the C3'-O(P) bond rupture of the 3'UMPH electron adduct, the reaction is exothermic and the barrier is even lower, 8.2 kcal mol(-1), which is in agreement with recent results for 3'-dTMPH and 5'-dTMPH (dTMPH=deoxythymidine monophosphate). Both the Mulliken atomic charges and unpaired-spin distribution play significant roles in the reactions.
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Affiliation(s)
- Ru Bo Zhang
- School of Science and the Institute for Chemical Physics, Beijing Institute of Technology, Beijing 100081, China
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39
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Stokes ST, Grubisic A, Li X, Ko YJ, Bowen KH. Photoelectron spectroscopy of the parent anions of the nucleotides, adenosine-5'-monophosphate and 2'deoxyadenosine-5'-monophosphate. J Chem Phys 2008; 128:044314. [PMID: 18247956 DOI: 10.1063/1.2823001] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The parent anions of the nucleotides, adenosine-5(')-monophosphate (AMPH) and 2(')deoxyadenosine-5(')-monophosphate (dAMPH) were generated in a novel source and their photoelectron spectra recorded with 3.49 eV photons. Vertical detachment energy (VDE) and the adiabatic electron affinity (EA(a)) values were extracted from each of the two spectra. Concurrently, Kobylecka et al. [J. Chem. Phys. 128, 044315 (2008)] conducted calculations which explored electron attachment to dAMPH. Based on the agreement between their calculated and our measured VDE and EA(a) values, we conclude that the dAMPH(-) anions studied in these experiments were formed by electron-induced, intramolecular, (barrier-free) proton-transfer as predicted by the calculations. Given the similarities between the photoelectron spectra of dAMPH(-) and AMPH(-), it is likely that AMPH(-) can be described in the same manner.
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Affiliation(s)
- Sarah T Stokes
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
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Kobyłecka M, Gu J, Rak J, Leszczynski J. Barrier-free proton transfer in the valence anion of 2'-deoxyadenosine-5'-monophosphate. II. A computational study. J Chem Phys 2008; 128:044315. [PMID: 18247957 DOI: 10.1063/1.2823002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The propensity of four representative conformations of 2(')-deoxyadenosine-5(')-monophosphate (5(')-dAMPH) to bind an excess electron has been studied at the B3LYP6-31++G(d,p) level. While isolated canonical adenine does not support stable valence anions in the gas phase, all considered neutral conformations of 5(')-dAMPH form adiabatically stable anions. The type of an anionic 5(')-dAMPH state, i.e., the valence, dipole bound, or mixed (valence/dipole bound), depends on the internal hydrogen bond(s) pattern exhibited by a particular tautomer. The most stable anion results from an electron attachment to the neutral syn-south conformer. The formation of this anion is associated with a barrier-free proton transfer triggered by electron attachment and the internal rotation around the C4(')-C5(') bond. The adiabatic electron affinity of the a_south-syn anion is 1.19 eV, while its vertical detachment energy is 1.89 eV. Our results are compared with the photoelectron spectrum (PES) of 5(')-dAMPH(-) measured recently by Stokes et al., [J. Chem. Phys. 128, 044314 (2008)]. The computational VDE obtained for the most stable anionic structure matches well with the experimental electron binding energy region of maximum intensity. A further understanding of DNA damage might require experimental and computational studies on the systems in which purine nucleotides are engaged in hydrogen bonding.
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Affiliation(s)
- Monika Kobyłecka
- Faculty of Chemistry, University of Gdańsk, 80-952 Gdańsk, Sobieskiego 18, Poland
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41
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Radiation Effects On DNA: Theoretical Investigations Of Electron, Hole And Excitation Pathways To DNA Damage. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/978-1-4020-8184-2_20] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
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Bernhard WA, Purkayastha S, Milligan JR. Which DNA damage is likely to be relevant in hormetic responses? Dose Response 2007; 6:184-95. [PMID: 18648576 DOI: 10.2203/dose-response.07-009.bernhard] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Working under the assumption that hormesis is triggered by specific types of DNA damage, this report focuses on the types of damage which form the signature of ionizing radiation. The key attribute of the signature is the clustering of damage, arising from clusters of energy deposition such that more than one site within a 10 base pair segment of DNA has been chemically altered. A brief overview is given on what is currently believed to be the primary components of clustered damage produced by the direct effect. The overview draws primarily on studies that utilize electron paramagnetic resonance to measure free radical intermediates and gel electrophoresis to measure clustered damage in plasmid DNA. Based on this information, the threshold for a radiation induced biological response is calculated.
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Affiliation(s)
- William A Bernhard
- Department of Biochemistry and Biophysics, University of Rochester, Rochester, NY 14642, USA.
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Stokes ST, Li X, Grubisic A, Ko YJ, Bowen KH. Intrinsic electrophilic properties of nucleosides: Photoelectron spectroscopy of their parent anions. J Chem Phys 2007; 127:084321. [PMID: 17764262 DOI: 10.1063/1.2774985] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
The nucleoside parent anions 2(')-deoxythymidine(-), 2(')-deoxycytidine(-), 2(')-deoxyadenosine(-), uridine(-), cytidine(-), adenosine(-), and guanosine(-) were generated in a novel source, employing a combination of infrared desorption, electron photoemission, and a gas jet expansion. Once mass selected, the anion photoelectron spectrum of each of these was recorded. In the three cases in which comparisons were possible, the vertical detachment energies and likely adiabatic electron affinities extracted from these spectra agreed well with the values calculated both by Richardson et al. [J. Am. Chem. Soc. 126, 4404 (2004)] and by Li et al. [Radiat. Res. 165, 721 (2006)]. Through the combination of our experimental results and their theoretical calculations, several implications emerge. (1) With the possible exception of dG(-), the parent anions of nucleosides exist, and they are stable. (2) These nucleoside anions are valence anions, and in most cases the negative charge is closely associated with the nucleobase moiety. (3) The nucleoside parent anions we have generated and studied are the negative ions of canonical, neutral nucleosides, similar to those found in DNA.
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Affiliation(s)
- Sarah T Stokes
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, USA
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Xie H, Xia F, Cao Z. Density Functional Study toward Understanding Dehydrogenation of the Adenine−Thymine Base Pair and Its Anion. J Phys Chem A 2007; 111:4384-90. [PMID: 17474725 DOI: 10.1021/jp0686137] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The dehydrogenated radicals and anions of Watson-Crick adenine-thymine (A-T) base pair have been investigated by the B3LYP/DZP++ approach. Calculations show that the dehydrogenated radicals and anions have relatively high stabilities compared with the single base adenine and thymine. The electron attachment to the A-T base pair and its derivatives significantly modifies the hydrogen bond interactions and results in remarkable structural changes. As for the dehydrogenated A-T radicals, they have relatively high electron affinities and different dehydrogenation properties with respect to their constituent elements. The relatively low-cost hydrogen eliminations correspond to the (N9)-H (adenine) and (N1)-H (thymine) bonds cleavage. Both dehydrogenation processes have Gibbs free energies of reaction DeltaG degrees of 13.4 and 17.2 kcal mol-1, respectively. The solvent water exhibits significant effect on electron attachment and dehydrogenation properties of the A-T base pair and its derivatives. In the dehydrogenating process, the anionic A-T fragment gradually changes its electronic configuration from pi* to sigma* state, like the single bases adenine and thymine.
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Affiliation(s)
- Hujun Xie
- Department of Chemistry and State Key Laboratory of Physical Chemistry of Solid Surfaces, Xiamen University, Xiamen 361005, China
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45
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Kumar A, Sevilla MD. Low-energy electron attachment to 5'-thymidine monophosphate: modeling single strand breaks through dissociative electron attachment. J Phys Chem B 2007; 111:5464-74. [PMID: 17429994 DOI: 10.1021/jp070800x] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mechanisms of low-energy electron (LEE) attachment and subsequent single-strand break (SSB) formation are investigated by density functional theory treatment of a simple model for DNA, i.e., the nucleotide, 5'-thymidine monophosphate (5'-dTMPH). In the present study, the C5'-O5' bond dissociation due to LEE attachment has been followed along the adiabatic as well as on the vertical (electron attached to the optimized geometry of the neutral molecule) anionic surfaces using B3LYP functional and 6-31G* and 6-31++G** basis sets. Surprisingly, it is found that the PES of C5'-O5' bond dissociation in the anion radicals have approximately the same barrier for both adiabatic and vertical pathways. These results provide support for the hypothesis that transiently bound electrons (shape resonances) to the virtual molecular orbitals of the neutral molecule likely play a key role in the cleavage of the sugar-phosphate C5'-O5' bond in DNA resulting in the direct formation of single strand breaks without significant molecular relaxation. To take into account the solvation effects, we considered the neutral and anion radical of 5'-dTMP surrounded by 5 or 11 water molecules with Na+ as a counterion. These structures were optimized using the B3LYP/6-31G** level of theory. We find the barrier height for adiabatic C5'-O5' bond dissociation of 5'-dTMP anion radical in aqueous environment is so substantially higher than in the gas phase that the adiabatic route will not contribute to DNA strand cleavage in aqueous systems. This result is in agreement with experiment.
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Affiliation(s)
- Anil Kumar
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, USA
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46
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Winstead C, McKoy V. Interaction of low-energy electrons with the purine bases, nucleosides, and nucleotides of DNA. J Chem Phys 2007; 125:244302. [PMID: 17199346 DOI: 10.1063/1.2424456] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The authors report results from computational studies of the interaction of low-energy electrons with the purine bases of DNA, adenine and guanine, as well as with the associated nucleosides, deoxyadenosine and deoxyguanosine, and the nucleotide deoxyadenosine monophosphate. Their calculations focus on the characterization of the pi* shape resonances associated with the bases and also provide general information on the scattering of slow electrons by these targets. Results are obtained for adenine and guanine both with and without inclusion of polarization effects, and the resonance energy shifts observed due to polarization are used to predict pi* resonance energies in associated nucleosides and nucleotides, for which static-exchange calculations were carried out. They observe slight shifts between the resonance energies in the isolated bases and those in the nucleosides.
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Affiliation(s)
- Carl Winstead
- A. A. Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125, USA
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Abstract
Thin films of the short single DNA strand, GCAT, in which one of the bases has been removed were bombarded with 3 to 15 eV electrons. The yield functions of the H(-), O(-) and OH(-) ions desorbed from these films exhibit a broad peak near 9 eV, which is attributed to dissociative electron attachment to the basic molecules. Whereas removal of any one of the bases considerably decreases N-glycosidic and backbone C-O bond scission, the creation of basic sites does not appreciably modify bond rupture leading to anion electron stimulated desorption. These seemingly contradictory results make it possible to propose a detailed mechanism leading to the transfer of electrons in the range 5-13 eV within DNA.
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Affiliation(s)
- Sylwia Ptasińska
- Groupe en Sciences des Radiations, Faculté de Médecine, Université de Sherbrooke, Sherbrooke, QC, Canada J1H 5N4.
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48
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Li X, Sevilla MD. DFT Treatment of Radiation Produced Radicals in DNA Model Systems. ADVANCES IN QUANTUM CHEMISTRY 2007. [DOI: 10.1016/s0065-3276(06)52004-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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