1
|
Anderson RF, Shinde SS, Andrau L, Leung B, Skene C, White JM, Lobachevsky PN, Martin RF. Chemical Repair of Radical Damage to the GC Base Pair by DNA-Bound Bisbenzimidazoles. J Phys Chem B 2024. [PMID: 38686959 DOI: 10.1021/acs.jpcb.4c01069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024]
Abstract
The migration of an electron-loss center (hole) in calf thymus DNA to bisbenzimidazole ligands bound in the minor groove is followed by pulse radiolysis combined with time-resolved spectrophotometry. The initially observed absorption spectrum upon oxidation of DNA by the selenite radical is consistent with spin on cytosine (C), as the GC• pair neutral radical, followed by the spectra of oxidized ligands. The rate of oxidation of bound ligands increased with an increase in the ratio (r) ligands per base pair from 0.005 to 0.04. Both the rate of ligand oxidation and the estimated range of hole transfer (up to 30 DNA base pairs) decrease with the decrease in one-electron reduction potential between the GC• pair neutral radical of ca. 1.54 V and that of the ligand radicals (E0', 0.90-0.99 V). Linear plots of log of the rate of hole transfer versus r give a common intercept at r = 0 and a free energy change of 12.2 ± 0.3 kcal mol-1, ascribed to the GC• pair neutral radical undergoing a structural change, which is in competition to the observed hole transfer along DNA. The rate of hole transfer to the ligands at distance, R, from the GC• pair radical, k2, is described by the relationship k2 = k0 exp(constant/R), where k0 includes the rate constant for surmounting a small barrier.
Collapse
Affiliation(s)
- Robert F Anderson
- School of Chemical Sciences, University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
- Auckland Cancer Society Research Centre, University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
| | - Sujata S Shinde
- Auckland Cancer Society Research Centre, University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand
| | - Laura Andrau
- School of Chemistry and Bio-21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne 3052, Australia
| | - Brenda Leung
- School of Chemistry and Bio-21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne 3052, Australia
| | - Colin Skene
- School of Chemistry and Bio-21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne 3052, Australia
| | - Jonathan M White
- School of Chemistry and Bio-21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne 3052, Australia
| | - Pavel N Lobachevsky
- Molecular Radiation Biology, Peter MacCallum Cancer Centre, Melbourne 3052, Australia
| | - Roger F Martin
- School of Chemistry and Bio-21 Molecular Science and Biotechnology Institute, University of Melbourne, Melbourne 3052, Australia
| |
Collapse
|
2
|
Spin Trapping Hydroxyl and Aryl Radicals of One-Electron Reduced Anticancer Benzotriazine 1,4-Dioxides. Molecules 2022; 27:molecules27030812. [PMID: 35164077 PMCID: PMC8840461 DOI: 10.3390/molecules27030812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2021] [Revised: 01/19/2022] [Accepted: 01/21/2022] [Indexed: 02/06/2023] Open
Abstract
Hypoxia in tumors results in resistance to both chemotherapy and radiotherapy treatments but affords an environment in which hypoxia-activated prodrugs (HAP) are activated upon bioreduction to release targeted cytotoxins. The benzotriazine 1,4-di-N-oxide (BTO) HAP, tirapazamine (TPZ, 1), has undergone extensive clinical evaluation in combination with radiotherapy to assist in the killing of hypoxic tumor cells. Although compound 1 did not gain approval for clinical use, it has spurred on the development of other BTOs, such as the 3-alkyl analogue, SN30000, 2. There is general agreement that the cytotoxin(s) from BTOs arise from the one-electron reduced form of the compounds. Identifying the cytotoxic radicals, and whether they play a role in the selective killing of hypoxic tumor cells, is important for continued development of the BTO class of anticancer prodrugs. In this study, nitrone spin-traps, combined with electron spin resonance, give evidence for the formation of aryl radicals from compounds 1, 2 and 3-phenyl analogues, compounds 3 and 4, which form carbon C-centered radicals. In addition, high concentrations of DEPMPO (5-(diethoxyphosphoryl)-5-methyl-1-pyrroline N-oxide) spin-trap the •OH radical. The combination of spin-traps with high concentrations of DMSO and methanol also give evidence for the involvement of strongly oxidizing radicals. The failure to spin-trap methyl radicals with PBN (N-tert-butylphenylnitrone) on the bioreduction of compound 2, in the presence of DMSO, implies that free •OH radicals are not released from the protonated radical anions of compound 2. The spin-trapping of •OH radicals by high concentrations of DEPMPO, and the radical species arising from DMSO and methanol give both direct and indirect evidence for the scavenging of •OH radicals that are involved in an intramolecular process. Hypoxia-selective cytotoxicity is not related to the formation of aryl radicals from the BTO compounds as they are associated with high aerobic cytotoxicity.
Collapse
|
3
|
Denisov SA, Ward S, Shcherbakov V, Stark AD, Kaczmarek R, Radzikowska-Cieciura E, Debnath D, Jacobs T, Kumar A, Sevilla MD, Pernot P, Dembinski R, Mostafavi M, Adhikary A. Modulation of the Directionality of Hole Transfer between the Base and the Sugar-Phosphate Backbone in DNA with the Number of Sulfur Atoms in the Phosphate Group. J Phys Chem B 2022; 126:430-442. [PMID: 34990129 PMCID: PMC8776618 DOI: 10.1021/acs.jpcb.1c09068] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
This work shows that S atom substitution in phosphate controls the directionality of hole transfer processes between the base and sugar-phosphate backbone in DNA systems. The investigation combines synthesis, electron spin resonance (ESR) studies in supercooled homogeneous solution, pulse radiolysis in aqueous solution at ambient temperature, and density functional theory (DFT) calculations of in-house synthesized model compound dimethylphosphorothioate (DMTP(O-)═S) and nucleotide (5'-O-methoxyphosphorothioyl-2'-deoxyguanosine (G-P(O-)═S)). ESR investigations show that DMTP(O-)═S reacts with Cl2•- to form the σ2σ*1 adduct radical -P-S[Formula: see text]Cl, which subsequently reacts with DMTP(O-)═S to produce [-P-S[Formula: see text]S-P-]-. -P-S[Formula: see text]Cl in G-P(O-)═S undergoes hole transfer to Gua, forming the cation radical (G•+) via thermally activated hopping. However, pulse radiolysis measurements show that DMTP(O-)═S forms the thiyl radical (-P-S•) by one-electron oxidation, which did not produce [-P-S[Formula: see text]S-P-]-. Gua in G-P(O-)═S is oxidized unimolecularly by the -P-S• intermediate in the sub-picosecond range. DFT thermochemical calculations explain the differences in ESR and pulse radiolysis results obtained at different temperatures.
Collapse
Affiliation(s)
- Sergey A. Denisov
- Institut de Chimie Physique, UMR 8000 CNRS/Université Paris-Saclay, Bât. 349, Orsay 91405 Cedex, France
| | - Samuel Ward
- Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI 48309-4479, USA
| | - Viacheslav Shcherbakov
- Institut de Chimie Physique, UMR 8000 CNRS/Université Paris-Saclay, Bât. 349, Orsay 91405 Cedex, France
| | - Alexander D. Stark
- Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI 48309-4479, USA
| | - Renata Kaczmarek
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Łódź, Poland
| | - Ewa Radzikowska-Cieciura
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Łódź, Poland
| | - Dipra Debnath
- Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI 48309-4479, USA
| | - Taisiya Jacobs
- Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI 48309-4479, USA
| | - Anil Kumar
- Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI 48309-4479, USA
| | - Michael D. Sevilla
- Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI 48309-4479, USA
| | - Pascal Pernot
- Institut de Chimie Physique, UMR 8000 CNRS/Université Paris-Saclay, Bât. 349, Orsay 91405 Cedex, France
| | - Roman Dembinski
- Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI 48309-4479, USA,Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Sienkiewicza 112, 90-363 Łódź, Poland
| | - Mehran Mostafavi
- Institut de Chimie Physique, UMR 8000 CNRS/Université Paris-Saclay, Bât. 349, Orsay 91405 Cedex, France
| | - Amitava Adhikary
- Department of Chemistry, Oakland University, 146 Library Drive, Rochester, MI 48309-4479, USA
| |
Collapse
|
4
|
The Two Faces of the Guanyl Radical: Molecular Context and Behavior. Molecules 2021; 26:molecules26123511. [PMID: 34207639 PMCID: PMC8227002 DOI: 10.3390/molecules26123511] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 05/29/2021] [Accepted: 06/01/2021] [Indexed: 12/16/2022] Open
Abstract
The guanyl radical or neutral guanine radical G(-H)• results from the loss of a hydrogen atom (H•) or an electron/proton (e–/H+) couple from the guanine structures (G). The guanyl radical exists in two tautomeric forms. As the modes of formation of the two tautomers, their relationship and reactivity at the nucleoside level are subjects of intense research and are discussed in a holistic manner, including time-resolved spectroscopies, product studies, and relevant theoretical calculations. Particular attention is given to the one-electron oxidation of the GC pair and the complex mechanism of the deprotonation vs. hydration step of GC•+ pair. The role of the two G(-H)• tautomers in single- and double-stranded oligonucleotides and the G-quadruplex, the supramolecular arrangement that attracts interest for its biological consequences, are considered. The importance of biomarkers of guanine DNA damage is also addressed.
Collapse
|
5
|
Warkhade SK, Singh RP, Das RS, Gaikwad G, Zodape SP, Pratap UR, Maldhure A, Wankhade AV. CoSe2 nanoflakes: An artificial nanoenzyme with excellent peroxidase like activity. INORG CHEM COMMUN 2021. [DOI: 10.1016/j.inoche.2021.108461] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
6
|
Anderson RF, Shinde SS, Maroz A, Reynisson J. The reduction potential of the slipped GC base pair in one-electron oxidized duplex DNA. Phys Chem Chem Phys 2020; 22:642-646. [PMID: 31822872 DOI: 10.1039/c9cp05544d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Redox equilibrium between the low potential aniline radical cation and the guanine in the GC base pair of duplex DNA has been established using pulse radiolysis. We relate the measurement of a radical one-electron reduction potential, E0', of 1.01 ± 0.03 V to the perturbation of the GC base pair to accommodate the neutral guanyl radical in an energetically more stable 'slipped' structure. The formation of the 'slipped' structure is exothermic by -11.4 kcal mol-1 as calculated by DFT, which is inline with our experimental results.
Collapse
Affiliation(s)
- Robert F Anderson
- Auckland Cancer Society Research Centre, University of Auckland, Private Bag 92019, Victoria Street West, Auckland 1142, New Zealand.
| | | | | | | |
Collapse
|
7
|
Tyugashev TE, Vorobjev YN, Kuznetsova AA, Lukina MV, Kuznetsov NA, Fedorova OS. Roles of Active-Site Amino Acid Residues in Specific Recognition of DNA Lesions by Human 8-Oxoguanine-DNA Glycosylase (OGG1). J Phys Chem B 2019; 123:4878-4887. [PMID: 31117610 DOI: 10.1021/acs.jpcb.9b02949] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Human 8-oxoguanine-DNA glycosylase (hOGG1) possesses very high specificity for 8-oxoguanine (oxoG), even though this damaged base differs from normal guanine by only two atoms. Our aim was to determine the roles of certain catalytically important amino acid residues in the hOGG1 enzymatic pathway and describe their involvement in the mechanism of DNA lesion recognition. Molecular dynamic simulation and pre-steady-state fluorescence kinetics were performed to analyze the conformational behavior of wild-type hOGG1 and mutants G42S, D268A, and K249Q, as well as damaged and undamaged DNA. A loss of electrostatic interactions in the K249Q mutant leads to the disruption of specific contacts in the active site of the enzyme and the loss of catalytic activity. The absence of residue Asp-268 abrogates the ability of the enzyme to fully flip out the oxoG base from the double helix, thereby disrupting proper positioning of the damaged base in the active site. Furthermore, substitution of Gly-42 with Ser, which forms a damage-specific H-bond with the N7 atom of the oxoG base, creates a stable H-bond between N7 of undamaged G and Oγ of Ser-42. Nevertheless, positioning of the undamaged base in the active site is unsuitable for catalytic hydrolysis of the N-glycosidic bond.
Collapse
Affiliation(s)
- Timofey E Tyugashev
- Institute of Chemical Biology and Fundamental Medicine , Lavrentyev Avenue 8 , Novosibirsk 630090 , Russia
| | - Yury N Vorobjev
- Institute of Chemical Biology and Fundamental Medicine , Lavrentyev Avenue 8 , Novosibirsk 630090 , Russia
| | - Alexandra A Kuznetsova
- Institute of Chemical Biology and Fundamental Medicine , Lavrentyev Avenue 8 , Novosibirsk 630090 , Russia
| | - Maria V Lukina
- Institute of Chemical Biology and Fundamental Medicine , Lavrentyev Avenue 8 , Novosibirsk 630090 , Russia
| | - Nikita A Kuznetsov
- Institute of Chemical Biology and Fundamental Medicine , Lavrentyev Avenue 8 , Novosibirsk 630090 , Russia.,Department of Natural Sciences , Novosibirsk State University , Pirogova Street 2 , Novosibirsk 630090 , Russia
| | - Olga S Fedorova
- Institute of Chemical Biology and Fundamental Medicine , Lavrentyev Avenue 8 , Novosibirsk 630090 , Russia.,Department of Natural Sciences , Novosibirsk State University , Pirogova Street 2 , Novosibirsk 630090 , Russia
| |
Collapse
|
8
|
Lin K, Burke A, King NB, Kahanda D, Mazaheripour A, Bartlett A, Dibble DJ, McWilliams MA, Taylor DW, Jocson J, Minary‐Jolandan M, Gorodetsky AA, Slinker JD. Enhancement of the Electrical Properties of DNA Molecular Wires through Incorporation of Perylenediimide DNA Base Surrogates. Chempluschem 2019; 84:416-419. [DOI: 10.1002/cplu.201800661] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 03/27/2019] [Indexed: 01/30/2023]
Affiliation(s)
- Kuo‐Yao Lin
- Department of Physics The University of Texas at Dallas 800 West Campbell Road, PHY 36 Richardson TX 75080-3021 USA
| | - Anthony Burke
- Department of Chemical Engineering and Materials Science 916 Engineering Tower University of California, Irvine Irvine CA 92697 USA
| | - Nolan B. King
- Department of Physics The University of Texas at Dallas 800 West Campbell Road, PHY 36 Richardson TX 75080-3021 USA
| | - Dimithree Kahanda
- Department of Physics The University of Texas at Dallas 800 West Campbell Road, PHY 36 Richardson TX 75080-3021 USA
| | - Amir Mazaheripour
- Department of Chemical Engineering and Materials Science 916 Engineering Tower University of California, Irvine Irvine CA 92697 USA
| | - Andrew Bartlett
- Department of Chemical Engineering and Materials Science 916 Engineering Tower University of California, Irvine Irvine CA 92697 USA
| | - David J. Dibble
- Department of Chemical Engineering and Materials Science 916 Engineering Tower University of California, Irvine Irvine CA 92697 USA
| | - Marc A. McWilliams
- Department of Physics The University of Texas at Dallas 800 West Campbell Road, PHY 36 Richardson TX 75080-3021 USA
| | - David W. Taylor
- Department of Physics The University of Texas at Dallas 800 West Campbell Road, PHY 36 Richardson TX 75080-3021 USA
| | - Jonah‐Micah Jocson
- Department of Chemical Engineering and Materials Science 916 Engineering Tower University of California, Irvine Irvine CA 92697 USA
| | - Majid Minary‐Jolandan
- Department of Mechanical Engineering The University of Texas at Dallas 800 W. Campbell Road, EC 38 Richardson TX 75080-3020 USA
| | - Alon A. Gorodetsky
- Department of Chemical Engineering and Materials Science 916 Engineering Tower University of California, Irvine Irvine CA 92697 USA
| | - Jason D. Slinker
- Department of Physics The University of Texas at Dallas 800 West Campbell Road, PHY 36 Richardson TX 75080-3021 USA
| |
Collapse
|
9
|
Keane PM, Kelly JM. Transient absorption and time-resolved vibrational studies of photophysical and photochemical processes in DNA-intercalating polypyridyl metal complexes or cationic porphyrins. Coord Chem Rev 2018. [DOI: 10.1016/j.ccr.2018.02.018] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
10
|
Zheng L, Greenberg MM. DNA Damage Emanating From a Neutral Purine Radical Reveals the Sequence Dependent Convergence of the Direct and Indirect Effects of γ-Radiolysis. J Am Chem Soc 2017; 139:17751-17754. [PMID: 29190086 DOI: 10.1021/jacs.7b10942] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Nucleobase radicals are the major intermediates generated by the direct (e.g., dA•+) and indirect (e.g., dA•) effects of γ-radiolysis. dA• was independently generated in DNA for the first time. The dA•+/dA• equilibrium, and consequently the reactivity in DNA, is significantly shifted toward the radical cation by a flanking dA. Tandem lesions emanating from dA• are the major products when the reactive intermediate is flanked by a 5'-dGT. In contrast, when dA• is flanked by dA, the increased dA•+ pKa results in DNA damage arising from hole transfer. This is the first demonstration that sequence effects lead to the intersection of the direct and indirect effects of ionizing radiation.
Collapse
Affiliation(s)
- Liwei Zheng
- Department of Chemistry, Johns Hopkins University , 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| | - Marc M Greenberg
- Department of Chemistry, Johns Hopkins University , 3400 N. Charles Street, Baltimore, Maryland 21218, United States
| |
Collapse
|
11
|
Keane PM, Kelly JM. Ground and excited state interactions of metalloporphyrin PtTMPyP4 with polynucleotides [poly(dG-dC)]2 and [poly(dA-dT)]2. Photochem Photobiol Sci 2016; 15:980-7. [PMID: 27377608 DOI: 10.1039/c6pp00105j] [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
The ground- and excited-state interactions of Pt(ii) meso-tetrakis(4-N-methylpyridyl)porphyrin (PtTMPyP4) with polynucleotides [poly(dG-dC)]2 and [poly(dA-dT)]2 have been investigated using UV/visible, circular dichroism, and steady-state and time-resolved emission spectroscopy. PtTMPyP4 intercalates into [poly(dG-dC)]2 with K∼ 10(6) M(-1). When bound to [poly(dG-dC)]2 in aerated solution there is a six-fold emission enhancement with 18 nm red-shift in emission maximum. Emission lifetimes are biexponential. In the presence of [poly(dA-dT)]2 at least two distinct groove-binding modes are observed, depending on the binding ratio. In [poly(dA-dT)]2 the emission intensity increases by a maximum factor of 17 with no shift in the emission spectrum. Three exponentials were required for lifetime fitting. The lower extent of emission enhancement in the presence of [poly(dG-dC)]2 suggests that a slow electron transfer may take place to guanine, which is significantly less efficient than that previously observed for PtTMPyP4 in the presence of guanosine 5'-monophosphate (GMP). The results are compared to those previously recorded with free base H2TMPyP4.
Collapse
Affiliation(s)
- Páraic M Keane
- School of Chemistry, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland.
| | | |
Collapse
|
12
|
Thapa B, Schlegel HB. Calculations of pKa's and redox potentials of nucleobases with explicit waters and polarizable continuum solvation. J Phys Chem A 2014; 119:5134-44. [PMID: 25291241 DOI: 10.1021/jp5088866] [Citation(s) in RCA: 99] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The SMD implicit solvation model augmented with one and four explicit water molecules was used to calculate pKa's and redox potentials of N-methyl-substituted nucleic acid bases guanine, adenine, cytosine, thymine, and uracil. Calculations were carried out with the B3LYP/6-31+G(d,p) level of theory. The same numbers of water molecules were hydrogen bonded to the neutral, protonated, and deprotonated nucleobases in their unoxidized and oxidized forms. The improvement in pKa1 involving neutrals and cations was modest. By contrast, the improvement in pKa2 involving neutrals and anions was quite significant, reducing the mean absolute error from 4.6 pKa units with no waters, to 2.6 with one water and 1.7 with four waters. For the oxidation of nucleobases, adding explicit waters did little to improve E(X(•),H(+)/XH), possibly because both species in the redox couple are neutral molecules at pH 7.
Collapse
Affiliation(s)
- Bishnu Thapa
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| | - H Bernhard Schlegel
- Department of Chemistry, Wayne State University, Detroit, Michigan 48202, United States
| |
Collapse
|
13
|
Burdak-Rothkamm S, Smith A, Lobachevsky P, Martin R, Prise KM. Radioprotection of targeted and bystander cells by methylproamine. Strahlenther Onkol 2014; 191:248-55. [PMID: 25245467 PMCID: PMC4338360 DOI: 10.1007/s00066-014-0751-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 09/02/2014] [Indexed: 11/25/2022]
Abstract
Introduction Radioprotective agents are of interest for application in radiotherapy for cancer and in public health medicine in the context of accidental radiation exposure. Methylproamine is the lead compound of a class of radioprotectors which act as DNA binding anti-oxidants, enabling the repair of transient radiation-induced oxidative DNA lesions. This study tested methylproamine for the radioprotection of both directly targeted and bystander cells. Methods T98G glioma cells were treated with 15 μM methylproamine and exposed to 137Cs γ-ray/X-ray irradiation and He2+ microbeam irradiation. Radioprotection of directly targeted cells and bystander cells was measured by clonogenic survival or γH2AX assay. Results Radioprotection of directly targeted T98G cells by methylproamine was observed for 137Cs γ-rays and X-rays but not for He2+ charged particle irradiation. The effect of methylproamine on the bystander cell population was tested for both X-ray irradiation and He2+ ion microbeam irradiation. The X-ray bystander experiments were carried out by medium transfer from irradiated to non-irradiated cultures and three experimental designs were tested. Radioprotection was only observed when recipient cells were pretreated with the drug prior to exposure to the conditioned medium. In microbeam bystander experiments targeted and nontargeted cells were co-cultured with continuous methylproamine treatment during irradiation and postradiation incubation; radioprotection of bystander cells was observed. Discussion and conclusion Methylproamine protected targeted cells from DNA damage caused by γ-ray or X-ray radiation but not He2+ ion radiation. Protection of bystander cells was independent of the type of radiation which the donor population received.
Collapse
|
14
|
Dong J, Song L, Yin JJ, He W, Wu Y, Gu N, Zhang Y. Co₃O₄ nanoparticles with multi-enzyme activities and their application in immunohistochemical assay. ACS APPLIED MATERIALS & INTERFACES 2014; 6:1959-1970. [PMID: 24387092 DOI: 10.1021/am405009f] [Citation(s) in RCA: 248] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Co3O4 nanoparticles (Co3O4 NPs), synthesized by the coprecipitation method, showed intrinsic catalase-like, peroxidase-like, and SOD-like activity. The catalytic activity of Co3O4 NPs was much higher than analogous Fe3O4 NPs. Co3O4's mechanisms of catalytic activity were analyzed in detail using the electron spin resonance (ESR) method, which confirmed that Co3O4 NPs don't follow the classical Fenton reactions with hydrogen peroxide the way Fe3O4 NPs do. The high redox potential of Co(3+)/Co(2+) was supposed to be the leading cause of the differences in both activity and mechanism with Fe3O4. Based on the high, peroxidase-like activity, a new immunohistochemical assay was designed in which the avastin antibody was conjugated onto the surface of Co3O4 NPs. The conjugates obtained were used to detect vascular endothelial growth factor (VEGF) that was overexpressed in tumor tissue. When the experimental and control groups were stained, there were clear distinctions between them. This study showed that there are many opportunities to improve the enzyme-like activities of nanomaterials and also to improve their potential applications for biocatalysis and bioassays, especially in relatively harsh conditions.
Collapse
Affiliation(s)
- Jinlai Dong
- State Key Laboratory of Bioelectronics, Jiangsu Key Laboratory for Biomaterials and Devices, School of Biological Science and Medical Engineering, Southeast University , Nanjing 210096, P.R. China
| | | | | | | | | | | | | |
Collapse
|
15
|
Rathod MA, Patel D, Das A, Tipparaju SR, Shinde SS, Anderson RF. Inhibition of radical-induced DNA strand breaks by water-soluble constituents of coffee: phenolics and caffeine metabolites. Free Radic Res 2013; 47:480-7. [DOI: 10.3109/10715762.2013.788167] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
16
|
Dodd MC. Potential impacts of disinfection processes on elimination and deactivation of antibiotic resistance genes during water and wastewater treatment. ACTA ACUST UNITED AC 2012; 14:1754-71. [DOI: 10.1039/c2em00006g] [Citation(s) in RCA: 299] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
|
17
|
Konigsfeld KM, Lee M, Urata SM, Aguilera JA, Milligan JR. Free terminal amines in DNA-binding peptides alter the product distribution from guanine radicals produced by single electron oxidation. Int J Radiat Biol 2011; 88:230-8. [PMID: 22124251 DOI: 10.3109/09553002.2012.643853] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
PURPOSE Electron deficient guanine radical species are major intermediates produced in DNA by the direct effect of ionizing irradiation. There is evidence that they react with amine groups in closely bound ligands to form covalent crosslinks. Crosslink formation is very poorly characterized in terms of quantitative rate and yield data. We sought to address this issue by using oligo-arginine ligands to model the close association of DNA and its binding proteins in chromatin. MATERIALS AND METHODS Guanine radicals were prepared in plasmid DNA by single electron oxidation. The product distribution derived from them was assayed by strand break formation after four different post-irradiation incubations. RESULTS We compared the yields of DNA damage produced in the presence of four ligands in which neither, one, or both of the amino and carboxylate termini were blocked with amides. Free carboxylate groups were unreactive. Significantly higher yields of heat labile sites were observed when the amino terminus was unblocked. The rate of the reaction was characterized by diluting the unblocked amino group with its amide blocked derivative. CONCLUSION These observations provide a means to develop quantitative estimates for the yields in which these labile sites are formed in chromatin by exposure to ionizing irradiation.
Collapse
Affiliation(s)
- Katie M Konigsfeld
- Department of Radiology, University of California at San Diego, La Jolla, California 92093-0610, USA
| | | | | | | | | |
Collapse
|
18
|
Transient spectroscopy of dipyridophenazine metal complexes which undergo photo-induced electron transfer with DNA. Coord Chem Rev 2011. [DOI: 10.1016/j.ccr.2011.04.007] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
19
|
Chatgilialoglu C, D’Angelantonio M, Kciuk G, Bobrowski K. New Insights into the Reaction Paths of Hydroxyl Radicals with 2′-Deoxyguanosine. Chem Res Toxicol 2011; 24:2200-6. [DOI: 10.1021/tx2003245] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
| | - Mila D’Angelantonio
- ISOF, Consiglio Nazionale delle Ricerche, Via P. Gobetti 101, 40129 Bologna, Italy
| | - Gabriel Kciuk
- Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw, Poland
| | - Krzysztof Bobrowski
- Institute of Nuclear Chemistry and Technology, Dorodna 16, 03-195 Warsaw, Poland
| |
Collapse
|
20
|
Liu H, Li G, Zhang L, Li J, Wang M, Bu Y. Electronic promotion effect of double proton transfer on conduction of DNA through improvement of transverse electronic communication of base pairs. J Chem Phys 2011; 135:134315. [DOI: 10.1063/1.3646308] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
|
21
|
Sviatenko L, Isayev O, Gorb L, Hill F, Leszczynski J. Toward robust computational electrochemical predicting the environmental fate of organic pollutants. J Comput Chem 2011; 32:2195-203. [DOI: 10.1002/jcc.21803] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 02/23/2011] [Accepted: 03/06/2011] [Indexed: 11/05/2022]
|
22
|
Khanduri D, Adhikary A, Sevilla MD. Highly oxidizing excited states of one-electron-oxidized guanine in DNA: wavelength and pH dependence. J Am Chem Soc 2011; 133:4527-37. [PMID: 21381665 PMCID: PMC3063320 DOI: 10.1021/ja110499a] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Excited states of one-electron-oxidized guanine in DNA are known to induce hole transfer to the sugar moiety and on deprotonation result in neutral sugar radicals that are precursors of DNA strand breaks. This work carried out in a homogeneous aqueous glass (7.5 M LiCl) at low temperatures (77-175 K) shows the extent of photoconversion of one-electron-oxidized guanine and the associated yields of individual sugar radicals are crucially controlled by the photon energy, protonation state, and strandedness of the oligomer. In addition to sugar radical formation, highly oxidizing excited states of one-electron-oxidized guanine are produced with 405 nm light at pH 5 and below that are able to oxidize chloride ion in the surrounding solution to form Cl(2)(•-) via an excited-state hole transfer process. Among the various DNA model systems studied in this work, the maximum amount of Cl(2)(•-) is produced with ds (double-stranded) DNA, where the one-electron-oxidized guanine exists in its cation radical form (G(•+):C). Thus, via excited-state hole transfer, the dsDNA is apparently able to protect itself from cation radical excited states by transfer of damage to the surrounding environment.
Collapse
Affiliation(s)
- Deepti Khanduri
- Department of Chemistry Oakland University Rochester, MI 48309
| | | | | |
Collapse
|
23
|
Adhikary A, Khanduri D, Pottiboyina V, Rice CT, Sevilla MD. Formation of aminyl radicals on electron attachment to AZT: abstraction from the sugar phosphate backbone versus one-electron oxidation of guanine. J Phys Chem B 2010; 114:9289-99. [PMID: 20575557 DOI: 10.1021/jp103403p] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Employing electron spin resonance (ESR) spectroscopy, we have characterized the radicals formed in 3'-azido-3'-deoxythymidine (3'-AZT) and in its 5'-analog 5'-azido-5'-deoxythymidine (5'-AZT) after electron attachment in gamma-irradiated aqueous (H(2)O or D(2)O) glassy (7.5 M LiCl) systems. ESR spectral studies and theoretical calculations show that the predominant site of electron capture in 3'-AZT and in 5'-AZT is at the azide group and not at the thymine moiety. The azide group in AZT is therefore more electron affinic than the most electron affinic DNA base, thymine. Electron attachment to 3'-AZT and 5'-AZT results in an unstable azide anion radical intermediate (RN(3)*(-)) that is too short-lived to be observed in our work even at 77 K. At 77 K, we observe the neutral aminyl radical (RNH*) after loss of N(2) from RN(3)*(-) followed by protonation of nitrene anion radical (RN*(-)) to give RNH*. The expected RN*(-) intermediate is not observed as protonation from water is complete at 77 K even under highly basic conditions. Formation of RND* in D(2)O solutions confirms water as the source of the NH proton in the RNH*. Our assignments to these radicals are aided by DFT calculations for hyperfine coupling constants that closely match the experimental values. On annealing to higher temperatures (ca. 160-170 K), RNH* undergoes bimolecular hydrogen abstraction reactions from the thymine methyl group and the sugar moiety resulting in the formation of the thymine allyl radical (UCH(2)*) and two sugar radicals, C3'* and C5'*. RNH* also results in one-electron oxidation of the guanine base in 3'-AZG. This work provides a potential mechanism for the reported radiosensitization effects of AZT.
Collapse
Affiliation(s)
- Amitava Adhikary
- Department of Chemistry, Oakland University, Rochester, Michigan 48309, USA
| | | | | | | | | |
Collapse
|
24
|
Warren JJ, Tronic TA, Mayer JM. Thermochemistry of proton-coupled electron transfer reagents and its implications. Chem Rev 2010; 110:6961-7001. [PMID: 20925411 PMCID: PMC3006073 DOI: 10.1021/cr100085k] [Citation(s) in RCA: 1182] [Impact Index Per Article: 84.4] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Jeffrey J. Warren
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700
| | - Tristan A. Tronic
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700
| | - James M. Mayer
- Department of Chemistry, University of Washington, Box 351700, Seattle, WA 98195-1700
| |
Collapse
|
25
|
Singh TA, Rao BSM, O'Neill P. Radical chemistry of 8-oxo-7,8-dihydro-2'-deoxyadenosine and 8-oxo-7,8-dihydro-2'-deoxyguanosine: a pulse radiolysis study. J Phys Chem B 2010; 114:16611-7. [PMID: 21090698 DOI: 10.1021/jp1070049] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The reactions of oxidizing ((•)OH, N(3)(•), and SO(4)(•-)) and reducing (e(aq)(-)) radicals with 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxoG) and 8-oxo-7,8-dihydro-2'-deoxyadenosine (8-oxoA) have been studied by pulse radiolysis to elucidate the initial free radical processes in their oxidation since these oxidized purines are readily oxidized in DNA. The second-order rate constants for the reaction of the (•)OH with 8-oxoA and 8-oxoG were determined to be 4.3 × 10(9) and 4.8 × 10(9) dm(3) mol(-1) s(-1), respectively. Similar values were also obtained with the N(3)(•) radical, the respective values being 8.8 × 10(9) and 3.8 × 10(9) dm(3) mol(-1) s(-1). The transient absorption spectrum following reaction of 8-oxoA with (•)OH is assigned to the C4- and C5-OH adducts which then undergo dehydration (k = 5.1 × 10(3) s(-1)) to give a reducing neutral N-centered radical. 8-oxoG, on the other hand, either reacts by H abstraction from the amino group attached to C2, which undergoes fast tautomerization or the resulting (•)OH adduct which rapidly dehydrates (k > 1.7 × 10(6) s(-1)) to give the species corresponding to the one-electron oxidized product. The transient absorption spectrum measured for the reaction of the N(3)(•) with 8-oxoG is identical to that obtained with the (•)OH at pH 10. The rate determining step is the formation of the radical cation which then rapidly loses a proton to form the neutral radical. It is estimated that 85% of (•)OH adducts are oxidizing while 13% are reducing. The yields of the reducing radicals on reaction of e(aq)(-) with 8-oxoA or 8-oxoG amount to ∼43 and 77% of the respective yield of e(aq)(-), whereas the extent of formation of any oxidizing radicals is ≤2%. In summary, radical intermediates from 8-oxoA or 8-oxoG and their redox potentials have been determined so that 8-oxoA and 8-oxoG, if preformed endogenously, may act as primary sinks for oxidized DNA damage if present close to DNA radicals induced radiolytically.
Collapse
Affiliation(s)
- Thounaojam Avinash Singh
- National Centre for Free Radical Research, Department of Chemistry, University of Pune, Pune 411007, India
| | | | | |
Collapse
|
26
|
Do TT, Tang VJ, Aguilera JA, Milligan JR. Structure reactivity relationship in the reaction of DNA guanyl radicals with hydroxybenzoates. Radiat Phys Chem Oxf Engl 1993 2010; 79:1144-1148. [PMID: 21966099 DOI: 10.1016/j.radphyschem.2010.06.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
In DNA, guanine bases are the sites from which electrons are most easily removed. As a result of hole migration to this stable location on guanine, guanyl radicals are major intermediates in DNA damage produced by the direct effect of ionizing radiation (ionization of the DNA itself and not through the intermediacy of water radicals). We have modeled this process by employing gamma irradiation in the presence of thiocyanate ions, a method which also produces single electron oxidized guanyl radicals in plasmid DNA in aqueous solution. The stable products formed in DNA from these radicals are detected as strand breaks after incubation with the FPG protein. When a phenolic compound is present in solution during gamma irradiation, the formation of guanyl radical species is decreased by electron donation from the phenol to the guanyl radical. We have quantified the rate of this reaction for four different phenolic compounds bearing carboxylate substituents as proton acceptors. A comparison of the rates of these reactions with the redox strengths of the phenolic compounds reveals that salicylate reacts ca. 10-fold faster than its structural analogs. This observation is consistent with a reaction mechanism involving a proton coupled electron transfer, because intra-molecular transfer of a proton from the phenolic hydroxyl group to the carboxylate group is possible only in salicylate, and is favored by the strong 6-membered ring intra-molecular hydrogen bond in this compound.
Collapse
Affiliation(s)
- Trinh T Do
- Department of Radiology, University of California at San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0610
| | | | | | | |
Collapse
|
27
|
Reaction of 2,4-dinitrofluorobenzene with enediamines. synthesis of cinnolines. Chem Heterocycl Compd (N Y) 2010. [DOI: 10.1007/s10593-010-0562-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
|
28
|
Wojdyla M, Smith JA, Vasudevan S, Quinn SJ, Kelly JM. Excited state behaviour of substituted dipyridophenazine Cr(III) complexes in the presence of nucleic acids. Photochem Photobiol Sci 2010; 9:1196-202. [PMID: 20617266 DOI: 10.1039/c0pp00110d] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photophysics and photochemistry of [Cr(phen)(2)(dppz)](3+) and its 11,12-substituted derivatives [Cr(phen)(2)(X(2)dppz)](3+) {X = Me or F} have been studied in the presence of purine nucleotides or DNA using steady state and time-resolved absorption and luminescence spectroscopy. 5'-Adenosine monophosphate (5'-AMP) shows only a weak interaction with the excited states of each complex. By contrast they are efficiently quenched by 5'-guanosine monophosphate (5'-GMP), consistent with photo-induced electron transfer. Laser flash photolysis spectroscopy in the presence of 5'-GMP suggests that both forward and back electron-transfers are rapid. All complexes also display a strong affinity for DNA and evidence for both static and dynamic quenching mechanisms is provided.
Collapse
Affiliation(s)
- Michal Wojdyla
- School of Chemistry, University of Dublin, Trinity College, College Green, Dublin 2, Republic of Ireland
| | | | | | | | | |
Collapse
|
29
|
Shinde SS, Maroz A, Hay MP, Patterson AV, Denny WA, Anderson RF. Characterization of radicals formed following enzymatic reduction of 3-substituted analogues of the hypoxia-selective cytotoxin 3-amino-1,2,4-benzotriazine 1,4-dioxide (tirapazamine). J Am Chem Soc 2010; 132:2591-9. [PMID: 20141134 DOI: 10.1021/ja908689f] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The mechanism by which the 1,2,4-benzotriazine 1,4-dioxide (BTO) class of bioreductive hypoxia-selective prodrugs (HSPs) form reactive radicals that kill cancer cells has been investigated by steady-state radiolysis, pulse radiolysis (PR), electron paramagnetic resonance (EPR), and density functional theory (DFT) calculations. Tirapazamine (TPZ, 3-amino BTO, 1) and a series of 3-substituted analogues, -H (2), -methyl (3), -ethyl (4), -methoxy (5), -ethoxymethoxy (6), and -phenyl (7), were reduced in aqueous solution under anaerobic steady-state radiolysis conditions, and their radicals were found to remove the substrates by short chain reactions of different lengths in the presence of formate ions. Multiple carbon-centered radical intermediates, produced upon anaerobic incubation of the compounds with cytochrome P(450) reductase enriched microsomes, were trapped by N-tert-butyl-alpha-phenylnitrone and observed using EPR. The highly oxidizing oxymethyl radical, from compound 5, was identified, and experimental spectra obtained for compounds 1, 2, 3, and 7 were well simulated after the inclusion of aryl radicals. The identification of a range of oxidizing radicals in the metabolism of the BTO compounds gives a new insight into the mechanism by which these HSPs can cause a wide variety of damage to biological targets such as DNA.
Collapse
Affiliation(s)
- Sujata S Shinde
- Department of Chemistry and Auckland Cancer Society Research Centre, The University of Auckland, Private Bag 92019, Auckland 1142, New Zealand
| | | | | | | | | | | |
Collapse
|
30
|
Affiliation(s)
- Joseph C. Genereux
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
| | - Jacqueline K. Barton
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125
| |
Collapse
|
31
|
Genereux JC, Boal AK, Barton JK. DNA-mediated charge transport in redox sensing and signaling. J Am Chem Soc 2010; 132:891-905. [PMID: 20047321 PMCID: PMC2902267 DOI: 10.1021/ja907669c] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The transport of charge through the DNA base-pair stack offers a route to carry out redox chemistry at a distance. Here we describe characteristics of this chemistry that have been elucidated and how this chemistry may be utilized within the cell. The shallow distance dependence associated with these redox reactions permits DNA-mediated signaling over long molecular distances in the genome and facilitates the activation of redox-sensitive transcription factors globally in response to oxidative stress. The long-range funneling of oxidative damage to sites of low oxidation potential in the genome also may provide a means of protection within the cell. Furthermore, the sensitivity of DNA charge transport to perturbations in base-pair stacking, as may arise with base lesions and mismatches, may be used as a route to scan the genome for damage as a first step in DNA repair. Thus, the ability of double-helical DNA in mediating redox chemistry at a distance provides a natural mechanism for redox sensing and signaling in the genome.
Collapse
Affiliation(s)
- Joseph C. Genereux
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125,
| | - Amie K. Boal
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125,
| | - Jacqueline K. Barton
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125,
| |
Collapse
|
32
|
Vasudevan S, Smith JA, Wojdyla M, McCabe T, Fletcher NC, Quinn SJ, Kelly JM. Substituted dipyridophenazine complexes of Cr(iii): Synthesis, enantiomeric resolution and binding interactions with calf thymus DNA. Dalton Trans 2010; 39:3990-8. [DOI: 10.1039/c000150c] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
|
33
|
Tsoi M, Do TT, Tang VJ, Aguilera JA, Milligan JR. Reduction of electron deficient guanine radical species in plasmid DNA by tyrosine derivatives. Org Biomol Chem 2010; 8:2553-9. [DOI: 10.1039/b922749k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
|