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Dong H, Wang HY, Xu YT, Zhang X, Chen HY, Xu JJ, Zhao WW. Iontronic Photoelectrochemical Biorecognition Probing. ACS Sens 2024; 9:988-994. [PMID: 38258286 DOI: 10.1021/acssensors.3c02544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
Herein, the first iontronic photoelectrochemical (PEC) biorecognition probing is devised by rational engineering of a dual-functional bioconjugate, i.e., a light-sensitive intercalated structural DNA, as a smart gating module confined within a nanotip, which could respond to both the incident light and biotargets of interest. Light stimulation of the bioconjugate could intensify the negative charge at the nano-orifice to sustain enhanced ionic current. The presence of proteins (e.g., acetylcholinesterase, AChE) or nucleic acids (e.g., microRNA (miR)-10b) could lead to bioconjugate release with altered ionic signaling. The practical applicability of the methodology is confirmed by AChE detection in human serum and miR-10b detection in single cells.
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Affiliation(s)
- Hang Dong
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China
| | - Hai-Yan Wang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China
| | - Yi-Tong Xu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China
| | - Xian Zhang
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China
| | - Hong-Yuan Chen
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China
| | - Jing-Juan Xu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China
| | - Wei-Wei Zhao
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China
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Kumari B, Huwaidi A, Robert G, Cloutier P, Bass AD, Sanche L, Wagner JR. Shape Resonances in DNA: Nucleobase Release, Reduction, and Dideoxynucleoside Products Induced by 1.3 to 2.3 eV Electrons. J Phys Chem B 2022; 126:5175-5184. [PMID: 35793462 DOI: 10.1021/acs.jpcb.2c01851] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Understanding the details of DNA damage caused by high-energy particles or photons is complicated by the multitude of reactive species, arising from the ionization and dissociation of H2O, DNA, and protein. In this work, oligonucleotides (ODNs) are irradiated with a beam of low-energy electrons of 1.3 to 2.3 eV, which can only induce damage via the decay of shape resonances into various dissociative electron attachment channels. Using LC-MS/MS analysis, the major products are the release of nonmodified nucleobases (NB; Cyt ≫ Thy ∼ Ade > Gua). Additional damage includes 5,6-dihydropyrimidines (dHT > dHU) and eight nucleosides with modified sugar moieties consisting of 2',3'- and 2',5'-dideoxynucleosides (ddG > ddA ∼ ddC > ddT). The distribution of products is remarkably different in a 16-mer ODN compared to that observed previously with thymidylyl-(3'-5')-thymidine. This difference is explained by electron delocalization occurring within a sufficiently long strand, the DEA theory of O'Malley, and recent time-dependent density functional theory calculations.
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Affiliation(s)
- Bhavini Kumari
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada
| | - Alaa Huwaidi
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada
| | - Gabriel Robert
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada
| | - Pierre Cloutier
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada
| | - Andrew D Bass
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada
| | - Léon Sanche
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada
| | - J Richard Wagner
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada
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3
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Huwaidi A, Kumari B, Robert G, Guérin B, Sanche L, Wagner JR. Profiling DNA Damage Induced by the Irradiation of DNA with Gold Nanoparticles. J Phys Chem Lett 2021; 12:9947-9954. [PMID: 34617774 DOI: 10.1021/acs.jpclett.1c02598] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
The presence of gold nanoparticles (AuNPs) greatly enhances the formation of DNA damage when exposed to therapeutic X-rays. Three types of DNA damage are assessed in irradiated DNA by enzymatic digestion coupled to liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis. The major type of damage is release of the four nonmodified nucleobases, with a bias toward the release of cytosine and thymine. The second most important pathway involves the formation of several common reduction and oxidation products of DNA. Lastly, eight unique modifications of the 2-deoxyribose moiety are formed, which includes the 2',3'- and 2',5'-dideoxynucleosides (ddNs) of the four canonical nucleosides. The yield of ddNs decreases in the following order: ddG > ddA > ddC > ddT. From the yield and distribution of products, most of the damage is considered to arise from the generation of Auger/low-energy electrons (LEEs) and their reaction with DNA.
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Affiliation(s)
- Alaa Huwaidi
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada
| | - Bhavini Kumari
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada
| | - Gabriel Robert
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada
| | - Brigitte Guérin
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada
| | - Léon Sanche
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada
| | - J Richard Wagner
- Département de Médecine Nucléaire et Radiobiologie, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12e Avenue Nord, Québec J1H 5N4, Canada
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4
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Uleanya KO, Dessent CEH. Investigating the mapping of chromophore excitations onto the electron detachment spectrum: photodissociation spectroscopy of iodide ion-thiouracil clusters. Phys Chem Chem Phys 2021; 23:1021-1030. [PMID: 33428696 DOI: 10.1039/d0cp05920j] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Laser photodissociation spectroscopy (3.1-5.7 eV) has been applied to iodide complexes of the non-native nucleobases, 2-thiouracil (2-TU), 4-thiouracil (4-TU) and 2,4-thiouracil (2,4-TU), to probe the excited states and intracluster electron transfer as a function of sulphur atom substitution. Photodepletion is strong for all clusters (I-·2-TU, I-·4-TU and I-·2,4-TU) and is dominated by electron detachment processes. For I-·4-TU and I-·2,4-TU, photodecay is accompanied by formation of the respective molecular anions, 4-TU- and 2,4-TU-, behaviour that is not found for other nucleobases. Notably, the I-·2TU complex does not fragment with formation of its molecular anion. We attribute the novel formation of 4-TU- and 2,4-TU- to the fact that these valence anions are significantly more stable than 2-TU-. We observe further similar behaviour for I-·4-TU and I-·2,4-TU relating to the general profile of their photodepletion spectra, since both strongly resemble the intrinsic absorption spectra of the respective uncomplexed thiouracil molecule. This indicates that the nucleobase chromophore excitations are determining the clusters' spectral profile. In contrast, the I-·2-TU photodepletion spectrum is dominated by the electron detachment profile, with the near-threshold dipole-bound excited state being the only distinct spectral feature. We discuss these observations in the context of differences in the dipole moments of the thionucleobases, and their impact on the coupling of nucleobase-centred transitions onto the electron detachment spectrum.
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Affiliation(s)
- Kelechi O Uleanya
- Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
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Diamantis P, Tavernelli I, Rothlisberger U. Redox Properties of Native and Damaged DNA from Mixed Quantum Mechanical/Molecular Mechanics Molecular Dynamics Simulations. J Chem Theory Comput 2020; 16:6690-6701. [PMID: 32926773 DOI: 10.1021/acs.jctc.0c00568] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The redox properties of two large DNA fragments composed of 39 base pairs, differing only by an 8-oxoguanine (8oxoG) defect replacing a guanine (G), were investigated in physiological conditions using mixed quantum mechanical/molecular mechanical (QM/MM) molecular dynamics simulations. The quantum region of the native fragment comprised 3 G-C base pairs, while one G was replaced by an 8oxoG in the defect fragment. The calculated values for the redox free energy are 6.55 ± 0.28 eV and 5.62 ± 0.30 eV for the native and the 8oxoG-containing fragment, respectively. The respective estimates for the reorganization free energy are 1.25 ± 0.18 eV and 1.00 ± 0.18 eV. Both reactions follow the Marcus theory for electron transfer. The large difference in redox potential between the two fragments shows that replacement of a G by an 8oxoG renders the DNA more easily oxidizable. This finding is in agreement with the suggestion that DNA fragments containing an 8oxoG defect can act as sinks of oxidative damage that protect the rest of the genome from assault. In addition, the difference in redox potential between the native and the defect DNA fragment indicates that a charge transfer-based mechanism for the recognition of DNA defects might be feasible, in line with recent suggestions based on experimental observations.
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Affiliation(s)
- Polydefkis Diamantis
- Laboratory of Computational Chemistry and Biochemistry, École Polytechnique Fédérale de Lausanne, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland
| | - Ivano Tavernelli
- Laboratory of Computational Chemistry and Biochemistry, École Polytechnique Fédérale de Lausanne, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland
| | - Ursula Rothlisberger
- Laboratory of Computational Chemistry and Biochemistry, École Polytechnique Fédérale de Lausanne, Swiss Federal Institute of Technology, CH-1015 Lausanne, Switzerland
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Vogel S, Ebel K, Heck C, Schürmann RM, Milosavljević AR, Giuliani A, Bald I. Vacuum-UV induced DNA strand breaks - influence of the radiosensitizers 5-bromouracil and 8-bromoadenine. Phys Chem Chem Phys 2019; 21:1972-1979. [PMID: 30633275 DOI: 10.1039/c8cp06813e] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Radiation therapy is a basic part of cancer treatment. To increase the DNA damage in carcinogenic cells and preserve healthy tissue at the same time, radiosensitizing molecules such as halogenated nucleobase analogs can be incorporated into the DNA during the cell reproduction cycle. In the present study 8.44 eV photon irradiation induced single strand breaks (SSB) in DNA sequences modified with the radiosensitizer 5-bromouracil (5BrU) and 8-bromoadenine (8BrA) are investigated. 5BrU was incorporated in the 13mer oligonucleotide flanked by different nucleobases. It was demonstrated that the highest SSB cross sections were reached, when cytosine and thymine were adjacent to 5BrU, whereas guanine as a neighboring nucleobase decreases the activity of 5BrU indicating that competing reaction mechanisms are active. This was further investigated with respect to the distance of guanine to 5BrU separated by an increasing number of adenine nucleotides. It was observed that the SSB cross sections were decreasing with an increasing number of adenine spacers between guanine and 5BrU until the SSB cross sections almost reached the level of a non-modified DNA sequence, which demonstrates the high sequence dependence of the sensitizing effect of 5BrU. 8BrA was incorporated in a 13mer oligonucleotide as well and the strand breaks were quantified upon 8.44 eV photon irradiation in direct comparison to a non-modified DNA sequence of the same composition. No clear enhancement of the SSB yield of the modified in comparison to the non-modified DNA sequence could be observed. Additionally, secondary electrons with a maximum energy of 3.6 eV were generated when using Si as a substrate giving rise to further DNA damage. A clear enhancement in the SSB yield can be ascertained, but to the same degree for both the non-modified DNA sequence and the DNA sequence modified with 8BrA.
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Affiliation(s)
- Stefanie Vogel
- Institute of Chemistry - Physical Chemistry, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany.
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7
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Zhang Y, He J, Gong WJ. Roles of quantum interference in modulating the spin-polarized transport induced by single-helical molecules. Chem Phys Lett 2019. [DOI: 10.1016/j.cplett.2019.136596] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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8
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Cercola R, Matthews E, Dessent CEH. Near-threshold electron transfer in anion-nucleobase clusters: does the identity of the anion matter? Mol Phys 2019. [DOI: 10.1080/00268976.2019.1596327] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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9
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Matthews E, Cercola R, Mensa-Bonsu G, Neumark DM, Dessent CEH. Photoexcitation of iodide ion-pyrimidine clusters above the electron detachment threshold: Intracluster electron transfer versus nucleobase-centred excitations. J Chem Phys 2018; 148:084304. [PMID: 29495768 DOI: 10.1063/1.5018168] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Laser photodissociation spectroscopy of the I-·thymine (I-·T) and I-·cytosine (I-·C) nucleobase clusters has been conducted for the first time across the regions above the electron detachment thresholds to explore the excited states and photodissociation channels. Although photodepletion is strong, only weak ionic photofragment signals are observed, indicating that the clusters decay predominantly by electron detachment. The photodepletion spectra of the I-·T and I-·C clusters display a prominent dipole-bound excited state (I) in the vicinity of the vertical detachment energy (∼4.0 eV). Like the previously studied I-·uracil (I-·U) cluster [W. L. Li et al., J. Chem. Phys. 145, 044319 (2016)], the I-·T cluster also displays a second excited state (II) centred at 4.8 eV, which we similarly assign to a π-π* nucleobase-localized transition. However, no distinct higher-energy absorption bands are evident in the spectra of the I-·C. Time-dependent density functional theory (TDDFT) calculations are presented, showing that while each of the I-·T and I-·U clusters displays a single dominant π-π* nucleobase-localized transition, the corresponding π-π* nucleobase transitions for I-·C are split across three separate weaker electronic excitations. I- and deprotonated nucleobase anion photofragments are observed upon photoexcitation of both I-·U and I-·T, with the action spectra showing bands (at 4.0 and 4.8 eV) for both the I- and deprotonated nucleobase anion production. The photofragmentation behaviour of the I-·C cluster is distinctive as its I- photofragment displays a relatively flat profile above the expected vertical detachment energy. We discuss the observed photofragmentation profiles of the I-·pyrimidine clusters, in the context of the previous time-resolved measurements, and conclude that the observed photoexcitations are primarily consistent with intracluster electron transfer dominating in the near-threshold region, while nucleobase-centred excitations dominate close to 4.8 eV. TDDFT calculations suggest that charge-transfer transitions [Iodide n (5p6) → Uracil σ*] may contribute to the cluster absorption profile across the scanned spectral region, and the possible role of these states is also discussed.
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Affiliation(s)
- Edward Matthews
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Rosaria Cercola
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Golda Mensa-Bonsu
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
| | - Daniel M Neumark
- Department of Chemistry, University of California, Berkeley, California 94720, USA and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Caroline E H Dessent
- Department of Chemistry, University of York, Heslington, York YO10 5DD, United Kingdom
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10
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Sanche L. Interaction of low energy electrons with DNA: Applications to cancer radiation therapy. Radiat Phys Chem Oxf Engl 1993 2016. [DOI: 10.1016/j.radphyschem.2016.05.008] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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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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12
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Behnia S, Fathizadeh S, Akhshani A. Modeling spin selectivity in charge transfer across the DNA/Gold interface. Chem Phys 2016. [DOI: 10.1016/j.chemphys.2016.08.016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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13
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Gu J, Wang J, Leszczynski J. Electron interaction with a DNA duplex: dCpdC:dGpdG. Phys Chem Chem Phys 2016; 18:13657-65. [PMID: 27139598 DOI: 10.1039/c6cp01408a] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Electron attachment to double-stranded cytosine-rich DNA, dCpdC:dGpdG, has been studied by density functional theory. This system represents a minimal descriptive unit of a cytosine-rich double-stranded DNA helix. A significant electron affinity for the formation of a cytosine-centered radical anion is revealed to be about 2.2 eV. The excess electron may reside on the nucleobase at the 5' position (dC˙(-)pdC:dGpdG) or at the 3' position (dCpdC˙(-):dGpdG). The inter-strand proton transfer between the radical anion centered cytosine (N3) and the paired guanine (HN1) results in the formation of radical anion center separated complexes dC1H˙pdC:dG2-H(-)pdG and dCpdC2H˙:dGpdG1-H(-). These distonic radical anions are found to be approximately 1 to 4 kcal mol(-1) more stable than the normal radical anions. Intra-strand cytosine π→π transition energies are below the electron detachment energy. Inter-strand π→π transitions of the excess electron from C to G are predicted to be less than 2.79 eV. Electron transfer might also be possible through the inter-strand base-jumping mode. An analysis of absorption visible spectra reveals the absorption bands ranging from 500 nm to 700 nm for the cytosine-rich radical anions of the DNA duplex. Electron attachment to cytidine oligomers might add color to the DNA duplex.
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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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14
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Karwowski BT. The influence of phosphorothioate on charge migration in single and double stranded DNA: a theoretical approach. Phys Chem Chem Phys 2015. [PMID: 26219639 DOI: 10.1039/c5cp01382h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In this study the influence of the phosphorothioate internucleotide bond on the electronic properties of single and double-stranded short nucleotides has been investigated at the M06-2X/6-31+G** level of theory in the gaseous phase. Due to the chirality of the phosphorus atom in a phosphorothioate (PT) internucleotide diester bond, the adiabatic/vertical mode of electron affinity/ionization potential, spin density and molecular orbital distribution, as well as structural analysis were taken under consideration for the single stranded (ss) R(P) and S(P) diastereomers of d[G(PS)G] and for double stranded (ds) d[G(PS)G]*d[C(PO)C], in comparison with the corresponding parent phosphate compounds. Moreover, the excitation states, HOMO and LUMO energies were calculated using a TD-DFT methodology at the M06-2X/6-31+G**//M06-2X/6-31++G** level of theory in the aqueous phase. The obtained results show that the PT plays a significant role in the case of ss-oligonucleotides, and to a much smaller extent in ds-oligomers.
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Affiliation(s)
- Boleslaw T Karwowski
- Food Science Department, Medical University of Lodz, ul. Muszynskiego 1, 90-151 Lodz, Poland.
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15
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Sequence dependence of electron-induced DNA strand breakage revealed by DNA nanoarrays. Sci Rep 2014; 4:7391. [PMID: 25487346 PMCID: PMC4260214 DOI: 10.1038/srep07391] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Accepted: 11/20/2014] [Indexed: 01/18/2023] Open
Abstract
The electronic structure of DNA is determined by its nucleotide sequence, which is for instance exploited in molecular electronics. Here we demonstrate that also the DNA strand breakage induced by low-energy electrons (18 eV) depends on the nucleotide sequence. To determine the absolute cross sections for electron induced single strand breaks in specific 13 mer oligonucleotides we used atomic force microscopy analysis of DNA origami based DNA nanoarrays. We investigated the DNA sequences 5′-TT(XYX)3TT with X = A, G, C and Y = T, BrU 5-bromouracil and found absolute strand break cross sections between 2.66 · 10−14 cm2 and 7.06 · 10−14 cm2. The highest cross section was found for 5′-TT(ATA)3TT and 5′-TT(ABrUA)3TT, respectively. BrU is a radiosensitizer, which was discussed to be used in cancer radiation therapy. The replacement of T by BrU into the investigated DNA sequences leads to a slight increase of the absolute strand break cross sections resulting in sequence-dependent enhancement factors between 1.14 and 1.66. Nevertheless, the variation of strand break cross sections due to the specific nucleotide sequence is considerably higher. Thus, the present results suggest the development of targeted radiosensitizers for cancer radiation therapy.
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Luo X, Zheng Y, Sanche L. DNA strand breaks and crosslinks induced by transient anions in the range 2-20 eV. J Chem Phys 2014; 140:155101. [PMID: 26792947 PMCID: PMC4716823 DOI: 10.1063/1.4870519] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
The energy dependence of the yields of single and double strand breaks (SSB and DSB) and crosslinks induced by electron impact on plasmid DNA films is measured in the 2-20 eV range. The yield functions exhibit two strong maxima, which are interpreted to result from the formation of core-excited resonances (i.e., transient anions) of the bases, and their decay into the autoionization channel, resulting in π → π* electronic transitions of the bases followed by electron transfer to the C-O σ* bond in the phosphate group. Occupancy of the σ* orbital ruptures the C-O bond of the backbone via dissociative electron attachment, producing a SSB. From a comparison of our results with those of other works, including theoretical calculations and electron-energy-loss spectra of the bases, the 4.6 eV peak in the SSB yield function is attributed to the resonance decay into the lowest electronically excited states of the bases; in particular, those resulting from the transitions 13A'(π2 → π3*) and 13A″(n2 → π3*) of thymine and 13A'(π → π*) of cytosine. The strongest peak at 9.6 eV in the SSB yield function is also associated with electron captured by excited states of the bases, resulting mostly from a multitude of higher-energy π → π* transitions. The DSB yield function exhibits strong maxima at 6.1 and 9.6 eV. The peak at 9.6 eV is probably related to the same resonance manifold as that leading to SSB, but the other at 6.1 eV may be more restricted to decay into the electronic state 13A' (π → π*) of cytosine via autoionization. The yield function of crosslinks is dominated by a broad peak extending over the 3.6-11.6 eV range with a sharper one at 17.6 eV. The different line shape of the latter function, compared to that of SSB and DSB, appears to be due to the formation of reactive radical sites in the initial supercoiled configuration of the plasmid, which react with the circular form (i.e., DNA with a SSB) to produce a crosslink.
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Affiliation(s)
- Xinglan Luo
- Research Institute of Photocatalysis, State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou 350002, People’s Republic of China
| | - Yi Zheng
- Research Institute of Photocatalysis, State Key Laboratory of Photocatalysis on Energy and Environment, Fuzhou University, Fuzhou 350002, People’s Republic of China
| | - Léon Sanche
- Group in the Radiation Sciences, Faculty of Medicine, Université de Sherbrooke, Sherbrooke, Quebec J1H 5N4, Canada
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17
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Gu J, Xie Y, Schaefer HF. Benchmarking the Electron Affinity of Uracil. J Chem Theory Comput 2014; 10:609-12. [DOI: 10.1021/ct400958d] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Jiande Gu
- Drug Design & Discovery Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, CAS, Shanghai 201203, People’s Republic of China
| | - Yaoming Xie
- Center for Computational
Quantum Chemistry, University of Georgia, Athens, Georgia 30602-2525, United States
| | - Henry F. Schaefer
- Center for Computational
Quantum Chemistry, University of Georgia, Athens, Georgia 30602-2525, United States
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18
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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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19
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Rosenberg RA, Symonds JM, Vijayalakshmi K, Mishra D, Orlando TM, Naaman R. The relationship between interfacial bonding and radiation damage in adsorbed DNA. Phys Chem Chem Phys 2014; 16:15319-25. [DOI: 10.1039/c4cp01649a] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Illustration showing that secondary electrons have a higher damage probability for thiolated DNA as opposed to unthiolated DNA, due to the former's higher density of LUMO states, which leads to more efficient capture of the low energy electrons.
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Affiliation(s)
- R. A. Rosenberg
- Advanced Photon Source
- Argonne National Laboratory
- Argonne, USA
| | - J. M. Symonds
- School of Chemistry and Biochemistry and School of Physics
- Georgia Institute of Technology
- Atlanta, USA
| | | | - Debabrata Mishra
- Department of Chemical Physics
- Weizmann Institute
- Rehovot 76100, Israel
| | - T. M. Orlando
- School of Chemistry and Biochemistry and School of Physics
- Georgia Institute of Technology
- Atlanta, USA
| | - R. Naaman
- Department of Chemical Physics
- Weizmann Institute
- Rehovot 76100, Israel
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20
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Hydrogen release from charged fragments of the uracil cation followed by their fragmentation: A DFT study. Chem Phys Lett 2013. [DOI: 10.1016/j.cplett.2013.07.082] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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21
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Boulanouar O, Fromm M, Mavon C, Cloutier P, Sanche L. Dissociative electron attachment to DNA-diamine thin films: impact of the DNA close environment on the OH- and O- decay channels. J Chem Phys 2013; 139:055101. [PMID: 23927286 PMCID: PMC3813476 DOI: 10.1063/1.4815967] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We measure the desorption of anions stimulated by the impact of 0-20 eV electrons on highly uniform thin films of plasmid DNA-diaminopropane. The results are accurately correlated with film thickness and composition by AFM and XPS measurements, respectively. Resonant structures in the H(-), O(-), and OH(-) yield functions are attributed to the decay of transient anions into the dissociative electron attachment (DEA) channel. The diamine induces ammonium-phosphate bridges along the DNA backbone, which suppresses the DEA O(-) channel and in counter-part increases considerably the desorption of OH(-). The close environment of the phosphate groups may therefore play an important role in modulating the rate and type of DNA damages induced by low energy electrons.
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Affiliation(s)
- Omar Boulanouar
- UMR CNRS 6249 Chrono-Environnement, Laboratoire de Chimie Physique et Rayonnements – Alain Chambaudet, LRC CEA, Université de Franche-Comté, 16 route de Gray, F-25030 Besançon cedex, France
| | - Michel Fromm
- UMR CNRS 6249 Chrono-Environnement, Laboratoire de Chimie Physique et Rayonnements – Alain Chambaudet, LRC CEA, Université de Franche-Comté, 16 route de Gray, F-25030 Besançon cedex, France
| | - Christophe Mavon
- UMR CNRS 6249 Chrono-Environnement, Laboratoire de Chimie Physique et Rayonnements – Alain Chambaudet, LRC CEA, Université de Franche-Comté, 16 route de Gray, F-25030 Besançon cedex, France
| | - Pierre Cloutier
- Groupe en Sciences des Radiations, Département de Médecine Nucléaire et de Radiobiologie, Faculté de Médecine, Université de Sherbrooke, Québec J1H 5N4, Canada
| | - Léon Sanche
- Groupe en Sciences des Radiations, Département de Médecine Nucléaire et de Radiobiologie, Faculté de Médecine, Université de Sherbrooke, Québec J1H 5N4, Canada
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22
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Kumar SVK, Pota T, Peri D, Dongre AD, Rao BJ. Low energy electron induced damage to plasmid DNA pQE30. J Chem Phys 2012; 137:045101. [DOI: 10.1063/1.4737182] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
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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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25
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Keller A, Bald I, Rotaru A, Cauët E, Gothelf KV, Besenbacher F. Probing electron-induced bond cleavage at the single-molecule level using DNA origami templates. ACS NANO 2012; 6:4392-9. [PMID: 22510060 DOI: 10.1021/nn3010747] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Low-energy electrons (LEEs) play an important role in nanolithography, atmospheric chemistry, and DNA radiation damage. Previously, the cleavage of specific chemical bonds triggered by LEEs has been demonstrated in a variety of small organic molecules such as halogenated benzenes and DNA nucleobases. Here we present a strategy that allows for the first time to visualize the electron-induced dissociation of single chemical bonds within complex, but well-defined self-assembled DNA nanostructures. We employ atomic force microscopy to image and quantify LEE-induced bond dissociations within specifically designed oligonucleotide targets that are attached to DNA origami templates. In this way, we use a highly selective approach to compare the efficiency of the electron-induced dissociation of a single disulfide bond with the more complex cleavage of the DNA backbone within a TT dinucleotide sequence. This novel technique enables the fast and parallel determination of DNA strand break yields with unprecedented control over the DNA's primary and secondary structure. Thus the detailed investigation of DNA radiation damage in its most natural environment, e.g., DNA nucleosomes constituting the chromatin, now becomes feasible.
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Affiliation(s)
- Adrian Keller
- Interdisciplinary Nanoscience Center (iNANO) and Danish National Research Foundation: Centre for DNA Nanotechnology (CDNA), Aarhus University, 8000 Aarhus C, Denmark.
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Kopyra J. Low energy electron attachment to the nucleotide deoxycytidine monophosphate: direct evidence for the molecular mechanisms of electron-induced DNA strand breaks. Phys Chem Chem Phys 2012; 14:8287-9. [PMID: 22573242 DOI: 10.1039/c2cp40847c] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reactions induced by the attachment of low energy electrons to an entire gas phase nucleotide (2'-deoxycytidine 5'-monophosphate) are reported for the first time. From the resonant attachment profiles information on the site of initial electron localization and from the observed ionic fragments information on final bond cleavage can be extracted.
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Affiliation(s)
- Janina Kopyra
- Department of Chemistry, Siedlce University, 3 Maja 54, 08-110 Siedlce, Poland.
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27
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Gupta A, Jaeger HM, Compaan KR, Schaefer HF. Electron attachment to the guanine-cytosine nucleic acid base pair and the effects of monohydration and proton transfer. J Phys Chem B 2012; 116:5579-87. [PMID: 22530702 DOI: 10.1021/jp211608b] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The guanine-cytosine (GC) radical anion and its interaction with a single water molecule is studied using ab initio and density functional methods. Z-averaged second-order perturbation theory (ZAPT2) was applied to GC radical anion for the first time. Predicted spin densities show that the radical character is localized on cytosine. The Watson-Crick monohydrated GC anion is compared to neutral GC·H2O, as well as to the proton-transferred analogue on the basis of structural and energetic properties. In all three systems, local minima are identified that correspond to water positioned in the major and minor grooves of macromolecular DNA. On the anionic surface, two novel structures have water positioned above or below the GC plane. On the neutral and anionic surfaces, the global minimum can be described as water interacting with the minor groove. These structures are predicted to have hydration energies of 9.7 and 11.8 kcal mol(-1), respectively. Upon interbase proton-transfer (PT), the anionic global minimum has water positioned in the major groove, and the hydration energy increases to 13.4 kcal mol(-1). PT GC·H2O(•-) has distonic character; the radical character resides on cytosine, while the negative charge is localized on guanine. The effects of proton transfer are further investigated through the computed adiabatic electron affinities (AEA) of GC and monohydrated GC, and the vertical detachment energies (VDE) of the corresponding anions. Monohydration increases the AEAs and VDEs by only 0.1 eV, while proton-transfer increases the VDEs substantially (0.8 eV). The molecular charge distribution of monohydrated guanine-cytosine radical anion depends heavily on interbase proton transfer.
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28
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Gu J, Liang G, Xie Y, Schaefer HF. Electron attachment to solvated dGpdG: effects of stacking on base-centered and phosphate-centered valence-bound radical anions. Chemistry 2012; 18:5232-8. [PMID: 22431283 DOI: 10.1002/chem.201103850] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Revised: 01/30/2012] [Indexed: 11/06/2022]
Abstract
To explore the nature of electron attachment to guanine-centered DNA single strands in the presence of a polarizable medium, a theoretical investigation of the DNA oligomer dinucleoside phosphate deoxyguanylyl-3',5'-deoxyguanosine (dGpdG) was performed by using density functional theory. Four different electron-distribution patterns for the radical anions of dGpdG in aqueous solution have been located as local minima on the potential energy surface. The excess electron is found to reside on the proton of the phosphate group (dGp(H-)dG), or on the phosphate group (dGp(.-)dG), or on the nucleobase at the 5' position (dG(.-)pdG), or on the nucleobase at the 3' position (dGpdG(.-)), respectively. These four radical anions are all expected to be electronically viable species under the influence of the polarizable medium. The predicted energetics of the radical anions follows the order dGp(.-)dG>dG(.-)pdG>dGpdG(.-)>dGp(H-)dG. The base-base stacking pattern in DNA single strands seems unaffected by electron attachment. On the contrary, intrastrand H-bonding is greatly influenced by electron attachment, especially in the formation of base-centered radical anions. The intrastrand H-bonding patterns revealed in this study also suggest that intrastrand proton transfer might be possible between successive guanines due to electron attachment to 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, Chinese Academy of Sciences, Shanghai 201203, P. R. China.
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29
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Gu J, Wang J, Leszczynski J. Electron Attachment to the Cytosine-Centered DNA Single Strands: Does Base Stacking Matter? J Phys Chem B 2012; 116:1458-66. [DOI: 10.1021/jp211386x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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
| | - Jing Wang
- Interdisciplinary Nanotoxicity
Center, Department of Chemistry, Jackson State University, Jackson,
Mississippi 39217, United States
| | - Jerzy Leszczynski
- Interdisciplinary Nanotoxicity
Center, Department of Chemistry, Jackson State University, Jackson,
Mississippi 39217, United States
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30
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31
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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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32
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Liu H, Walker LA, Doerksen RJ. DFT study on the radical anions formed by primaquine and its derivatives. Chem Res Toxicol 2011; 24:1476-85. [PMID: 21699254 DOI: 10.1021/tx200094v] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The electron affinities (EA) of the 8-aminoquinoline antimalarial drug primaquine and several of its metabolites were studied using the density functional theory method. We first considered six substituents at the 5-position, -CH(3), -OH, -OCH(3), -Ph, -OPh, and -CHO. We found that in the gas phase the adiabatic EAs are similar to that of the parent primaquine for the -CH(3), -OH, and -OCH(3) substituents. In contrast, the -Ph, -OPh, and -CHO substituents all markedly increase the adiabatic EA. However, only the -CHO substituted compound is predicted to form a stable covalently bound radical anion in the gas phase due to its significant positive vertical EA relative to that of the parent primaquine. In addition, when the 8-position is substituted by the N-hydroxyl group or a quinone-imine structure is formed, the electron capture ability is significantly increased. In aqueous solution, all these molecules have significantly larger adiabatic EAs than in the gas phase. In addition, all of the vertical EAs are positive in aqueous solution. The implications of these findings for contributing to our mechanistic understanding of the red cell toxicity of 8-aminoquinoline compounds are further discussed.
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Affiliation(s)
- Haining Liu
- Department of Medicinal Chemistry, University of Mississippi, Mississippi 38677, USA
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Markus TZ, Daube SS, Naaman R. Cooperative effect in the electronic properties of human telomere sequence. J Phys Chem B 2011; 114:13897-903. [PMID: 20942452 DOI: 10.1021/jp1064038] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The contribution of sequence elements of human telomere DNA to the interaction of DNA with electrons has been analyzed. By applying wavelength dependent low-energy photoelectron transmission and two-photon photoemission spectroscopy, we investigated the density of states of DNA oligomers with partial sequence elements of the human telomere assembled as monolayers on gold. The findings demonstrate the role of the resonance states in the DNA in accepting electrons and the effect of the sequence on these states. When guanine (G) bases are clustered together, the resonance negative ion state is stabilized, as compared to oligomers containing the same number of G bases but distributed within the sequence. The electron-capturing probability of the human telomere-like oligomer, a sequence with an additional single adenine (A) base adjacent to the G cluster, is dramatically enhanced compared to the other oligomers studied, most likely due to the enhancement of the density of states near the highest occupied molecular orbital.
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Affiliation(s)
- Tal Z Markus
- Department of Chemical Physics, Weizmann Institute, Rehovot 76100, Israel
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Gu J, Wong NB, Xie Y, Schaefer FH. Electron attachment to a hydrated DNA duplex: the dinucleoside phosphate deoxyguanylyl-3',5'-deoxycytidine. Chemistry 2011; 16:13155-62. [PMID: 20922718 DOI: 10.1002/chem.201001306] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The minimal essential section of DNA helices, the dinucleoside phosphate deoxyguanylyl-3',5'-deoxycytidine dimer octahydrate, [dGpdC](2), has been constructed, fully optimized, and analyzed by using quantum chemical methods at the B3LYP/6-31+G(d,p) level of theory. Study of the electrons attached to [dGpdC](2) reveals that DNA double strands are capable of capturing low-energy electrons and forming electronically stable radical anions. The relatively large vertical electron affinity (VEA) predicted for [dGpdC](2) (0.38 eV) indicates that the cytosine bases are good electron captors in DNA double strands. The structure, charge distribution, and molecular orbital analysis for the fully optimized radical anion [dGpdC](2)(·-) suggest that the extra electron tends to be redistributed to one of the cytosine base moieties, in an electronically stable structure (with adiabatic electron affinity (AEA) 1.14 eV and vertical detachment energy (VDE) 2.20 eV). The structural features of the optimized radical anion [dGpdC](2)(·-) also suggest the probability of interstrand proton transfer. The interstrand proton transfer leads to a distonic radical anion [d(G-H)pdC:d(C+H)pdG](·-), which contains one deprotonated guanine anion and one protonated cytosine radical. This distonic radical anion is predicted to be more stable than [dGpdC](2)(·-). Therefore, experimental evidence for electron attachment to the DNA double helices should be related to [d(G-H)pdC:d(C+H)pdG](·-) complexes, for which the VDE might be as high as 2.7 eV (in dry conditions) to 3.3 eV (in fully hydrated conditions). Effects of the polarizable medium have been found to be important for increasing the electron capture ability of the dGpdC dimer. The ultimate AEA value for cytosine in DNA duplexes is predicted to be 2.03 eV in aqueous solution.
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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, P. R. China.
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35
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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, Xie Y, Schaefer HF. Electron attachment to hydrated oligonucleotide dimers: guanylyl-3',5'-cytidine and cytidylyl-3',5'-guanosine. Chemistry 2010; 16:5089-96. [PMID: 20349466 DOI: 10.1002/chem.200902977] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The dinucleoside phosphate deoxycytidylyl-3',5'-deoxyguanosine (dCpdG) and deoxyguanylyl-3',5'-deoxycytidine (dGpdC) systems are among the largest to be studied by reliable theoretical methods. Exploring electron attachment to these subunits of DNA single strands provides significant progress toward definitive predictions of the electron affinities of DNA single strands. The adiabatic electron affinities of the oligonucleotides are found to be sequence dependent. Deoxycytidine (dC) on the 5' end, dCpdG, has larger adiabatic electron affinity (AEA, 0.90 eV) than dC on the 3' end of the oligomer (dGpdC, 0.66 eV). The geometric features, molecular orbital analyses, and charge distribution studies for the radical anions of the cytidine-containing oligonucleotides demonstrate that the excess electron in these anionic systems is dominantly located on the cytosine nucleobase moiety. The pi-stacking interaction between nucleobases G and C seems unlikely to improve the electron-capturing ability of the oligonucleotide dimers. The influence of the neighboring base on the electron-capturing ability of cytosine should be attributed to the intensified proton accepting-donating interaction between the bases. The present investigation demonstrates that the vertical detachment energies (VDEs) of the radical anions of the oligonucleotides dGpdC and dCpdG are significantly larger than those of the corresponding nucleotides. Consequently, reactions with low activation barriers, such as those for O-C sigma bond and N-glycosidic bond breakage, might be expected for the radical anions of the guanosine-cytosine mixed oligonucleotides.
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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, P. R. China.
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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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38
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Solomun T, Seitz H, Sturm H. DNA damage by low-energy electron impact: dependence on guanine content. J Phys Chem B 2010; 113:11557-9. [PMID: 19645513 DOI: 10.1021/jp905263x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Single-stranded DNA oligonucleotides (33-mers) containing different numbers of guanines (n=1-4) were tethered to a gold surface and exposed to 1 eV electrons. The electrons induced DNA damage, which was analyzed with fluorescence and infrared spectroscopy methods. The damage was identified as strand breaks and found to correlate linearly with the number of guanines in the sequence. This sequence dependence indicates that the electron capture by the DNA bases plays an important role in the damage reaction mechanism.
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Affiliation(s)
- T Solomun
- Institute of Chemistry and Biochemistry, Free University Berlin, Takustrasse 3, D-14195 Berlin, Germany.
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39
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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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40
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Wang CR, Nguyen J, Lu QB. Bond breaks of nucleotides by dissociative electron transfer of nonequilibrium prehydrated electrons: a new molecular mechanism for reductive DNA damage. J Am Chem Soc 2009; 131:11320-2. [PMID: 19634911 DOI: 10.1021/ja902675g] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
DNA damage is a central mechanism in the pathogenesis and treatment of human diseases, notably cancer. Little is known about reductive DNA damage in causing genetic mutations during oncogenesis and killing cancer cells during radiotherapy. The prehydrated electron (e(-)(pre)) has the highest yield among all the radicals generated in cells during ionizing radiation and has subpicosecond lifetimes (10(-13) s) and energies below 0 eV, but its role in DNA damage is unknown. In this work, our real-time measurements by femtosecond time-resolved laser spectroscopy have revealed that while adenine and cytosine can effectively trap an e(-)(pre) to form stable anions, thymidine and especially guanine are highly susceptible to dissociative electron transfer of e(-)(pre), leading to bond dissociation in DNA. Our finding demonstrates a dissociative electron transfer pathway for reductive DNA damage that might be related to various diseases such as cancer and stroke. Moreover, this finding challenges the conventional notion that damage to the genome is mainly induced by the oxidizing OH* radical and might eventually lead to improved radiotherapy of cancer and radioprotection of humans.
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Affiliation(s)
- Chun-Rong Wang
- Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada
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41
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Paul A, Bezer S, Venkatramani R, Kocsis L, Wierzbinski E, Balaeff A, Keinan S, Beratan DN, Achim C, Waldeck DH. Role of nucleobase energetics and nucleobase interactions in single-stranded peptide nucleic acid charge transfer. J Am Chem Soc 2009; 131:6498-507. [PMID: 19382798 DOI: 10.1021/ja9000163] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Self-assembled monolayers of single-stranded (ss) peptide nucleic acids (PNAs) containing seven nucleotides (TTTXTTT), a C-terminus cysteine, and an N-terminus ferrocene redox group were formed on gold electrodes. The PNA monomer group (X) was selected to be either cytosine (C), thymine (T), adenine (A), guanine (G), or a methyl group (Bk). The charge transfer rate through the oligonucleotides was found to correlate with the oxidation potential of X. Kinetic measurements and computational studies of the ss-PNA fragments show that a nucleobase mediated charge transport mechanism in the deep tunneling superexchange regime can explain the observed dependence of the kinetics of charge transfer on the PNA sequence. Theoretical analysis suggests that the charge transport is dominantly hole-mediated and takes place through the filled bridge orbitals. The strongest contribution to conductance comes from the highest filled orbitals (HOMO, HOMO-1, and HOMO-2) of individual bases, with a rapid drop off in contributions from lower lying filled orbitals. Our studies further suggest that the linear correlation observed between the experimental charge transfer rates and the oxidation potential of base X arises from weak average interbase couplings and similar stacking geometries for the four TTTXTTT systems.
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Affiliation(s)
- Amit Paul
- Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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42
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Gu J, Xie Y, Schaefer HF. Electron attachment to oligonucleotide dimers in water: Microsolvation-assisted base-stacking forms. Chem Phys Lett 2009. [DOI: 10.1016/j.cplett.2009.03.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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43
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Duncan Lyngdoh RH, Schaefer HF. Elementary lesions in DNA subunits: electron, hydrogen atom, proton, and hydride transfers. Acc Chem Res 2009; 42:563-72. [PMID: 19231845 DOI: 10.1021/ar800077q] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
When DNA is damaged by ionizing radiation, the genes in a cell may acquire mutations or the cell could die. The smallest known DNA-damaging unit is an electron, often low-energy secondary electrons. Additional electrons and transfers involving hydrogen atoms, protons, and hydride anions can damage DNA subunits, including individual nucleobases and nucleoside pairs. Researchers would like to better understand the molecular mechanisms involved in DNA damage from ionizing radiation. In this Account, we highlight our theoretical investigations of the molecular mechanisms of DNA damage using quantum mechanical models. Our investigations use robust theoretical methods with computations conducted in the gas phase and with solution models. We calculate adiabatic electron affinities (AEAs), which describe the energetics of electronic attachment to closed-shell DNA subunits, for the free bases, nucleosides, nucleotides, base pairs, and single and double DNA strand units. Electron affinities for free nucleobases yield the order uracil > thymine > cytosine > guanine > adenine and the same order for the DNA nucleosides, mononucleotides, and nucleoside 3',5'-diphosphates. AEA values increase steadily with the size and complexity of the system because of greater hydration, glycosylation, nucleotide formation, and base pairing. We predict and experimental results partially confirm that most of the more complex and hydrated species are observable as radical anions. Our modeling studies indicate that depyrimidination reactions of radical anion nucleosides release cytosine more often than thymine. Recent experimental results support those findings. Our theoretical studies of DNA base-pair radical anions predict increases in electron affinity accompanying H bonding and solvation. Electron addition facilitates some proton transfers in these pairs, which results in strongly perturbed pairing configurations. Of all nucleobase moieties within the more complex radical anion systems, thymine is best able to retain a negative charge. Charge and spin are well-separated in some of these systems. Radical species derived via hydrogen abstraction from DNA subunits yield large AEA values because they form closed-shell anions. Our studies predict single-strand breaks following H abstraction from nucleotides. Some H-abstraction processes in the DNA base pairs lead to severe distortions in pairing configuration based on our calculations. This body of systematic theoretical studies provides realistic descriptions of some events that lead to elementary DNA lesions, while providing rationalizations for many observed phenomena. Such approaches can lead to the design of new experiments, which would contribute to our understanding of the chemical physics of nucleic acids.
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Affiliation(s)
| | - Henry F. Schaefer
- Center for Computational Chemistry, University of Georgia, Athens, Georgia 30602
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44
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Markus TZ, Daube SS, Naaman R, Fleming AM, Muller JG, Burrows CJ. Electronic structure of DNA--unique properties of 8-oxoguanosine. J Am Chem Soc 2009; 131:89-95. [PMID: 19128174 DOI: 10.1021/ja804177j] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
8-Oxo-7,8-dihydroguanosine (8-oxoG) is among the most common forms of oxidative DNA damage found in human cells. The question of damage recognition by the repair machinery is a long standing one, and it is intriguing to suggest that the mechanism of efficiently locating damage within the entire genome might be related to modulations in the electronic properties of lesions compared to regular bases. Using laser-based methods combined with organizing various oligomers self-assembled monolayers on gold substrates, we show that indeed 8-oxoG has special electronic properties. By using oligomers containing 8-oxoG and guanine bases which were inserted in an all thymine sequences, we were able to determine the energy of the HOMO and LUMO states and the relative density of electronic states below the vacuum level. Specifically, it was found that when 8-oxoG is placed in the oligomer, the HOMO state is at higher energy than in the other oligomers studied. In contrast, the weakly mutagenic 8-oxo-7,8-dihydroadenosine (8-oxoA) has little or no effect on the electronic properties of DNA.
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Affiliation(s)
- Tal Z Markus
- Department of Chemical Physics, Chemical Research Support, Weizmann Institute, Rehovot 76100, Israel
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45
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Seal P, Jha PC, Ågren H, Chakrabarti S. Magnetic interactions in dehydrogenated Guanine–Cytosine base pair. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.09.069] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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46
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Bald I, Dąbkowska I, Illenberger E. Probing Biomolecules by Laser-Induced Acoustic Desorption: Electrons at Near Zero Electron Volts Trigger Sugar-Phosphate Cleavage. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200803382] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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47
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Bald I, Dąbkowska I, Illenberger E. Probing Biomolecules by Laser-Induced Acoustic Desorption: Electrons at Near Zero Electron Volts Trigger Sugar-Phosphate Cleavage. Angew Chem Int Ed Engl 2008; 47:8518-20. [DOI: 10.1002/anie.200803382] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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48
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Ramos MMD, Correia HMG. Modelling the effect of structure and base sequence on DNA molecular electronics. NANOTECHNOLOGY 2008; 19:375202. [PMID: 21832544 DOI: 10.1088/0957-4484/19/37/375202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
DNA is a material that has the potential to be used in nanoelectronic devices as an active component. However, the electronic properties of DNA responsible for its conducting behaviour remain controversial. Here we use a self-consistent quantum molecular dynamics method to study the effect of DNA structure and base sequence on the energy involved when electrons are added or removed from isolated molecules and the transfer of the injected charge along the molecular axis when an electric field is applied. Our results show that the addition or removal of an electron from DNA molecules is most exothermic for poly(dC)-poly(dG) in its B-form and poly(dA)-poly(dT) in its A-form, and least exothermic in its Z-form. Additionally, when an electric field is applied to a charged DNA molecule along its axis, there is electron transfer through the molecule, regardless of the number and sign of the injected charge, the molecular structure and the base sequence. Results from these simulations provide useful information that is hard to obtain from experiments and needs to be considered for further modelling aiming to improve charge transport efficiency in nanoelectronic devices based on DNA.
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Affiliation(s)
- M M D Ramos
- Departamento de Física, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal
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49
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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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50
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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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