How Easily Oxidizable Is DNA? One-Electron Reduction Potentials of Adenosine and Guanosine Radicals in Aqueous Solution

Steenken, S.; Jovanović, Slobodan V.

doi:10.1021/ja962255b

Cited by 1,394 publications

(1,484 citation statements)

References 25 publications

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“…The reduction potential of guanine is E 7 = 1.29 V vs NHE). 6 These reduction potentials suggest that both the CO 3 •− and BPT •+ radicals can oxidize guanine by oneelectron transfer mechanisms. The differences in base sequence effects on the electron transfer rate constants can be explained by considering the classical Marcus electron transfer equations 46 that defines the rate constant of electron transfer, k et , as follows: (16) where ΔG 0 is the free energy term that is proportional to the differences in redox potentials of the electron donor and acceptor couple, and λ is the reorganization energy.…”

Section: Kinetics Of Dna Oxidation By Co 3 •− Radicalsmentioning

confidence: 99%

Oxidation of Guanine in G, GG, and GGG Sequence Contexts by Aromatic Pyrenyl Radical Cations and Carbonate Radical Anions: Relationship between Kinetics and Distribution of Alkali-Labile Lesions

et al. 2008

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Oxidatively generated DNA damage induced by the aromatic radical cation of the pyrene derivative 7,8,9,10-tetrahydroxytetrahydrobenzo[a]pyrene (BPT), and by carbonate radicals anions, was monitored from the initial one-electron transfer, or hole injection step, to the formation of hot alkali-labile chemical end-products monitored by gel electrophoresis. The fractions of BPT molecules bound to double-stranded 20-35-mer oligonucleotdes with noncontiguous guanines G, and grouped as contiguous GG and GGG sequences, were determined by a fluorescence quenching method. Utilizing intense nanosecond 355 nm Nd: Yag laser pulses, the DNA-bound BPT molecules were photoionized to BPT •+ radicals by a consecutive two-photon ionization mechanism. The BPT •+ radicals thus generated within the duplexes selectively oxidize guanine by intraduplex electron transfer reactions, and the rate constants of these reactions follow the trend 5′-..GGG.. > 5′-..GG.. > 5′-..G… In the case of CO 3 •− radicals, the oxidation of guanine occurs by intermolecular collision pathways and the bimolecular rate constants are independent of base sequence context. However, the distributions of the end-products generated by CO 3 •− radicals, as well as by BPT •+ , is base sequence context-dependent and is greater than in isolated guanines at the 5′-G in 5′-…GG… sequences, and the first two 5′-guanines in the 5′-..GGG sequences. These results help to clarify the conditions that lead to a similar or different base sequence dependence of the initial hole injection step and the final distribution of oxidized, alkalilabile guanine products. In the case of the intermolecular one-electron oxidant CO 3 •− , the rate constant of hole injection is similar for contiguous and isolated guanines, but the subsequent equilibration of holes by hopping favors trapping and product formation at contiguous guanines, and the sequence dependence of these two phenomena are not correlated. In contrast, in the case of the DNA bound oxidant BPT •+ , the hole injection rate constants, as well as hole equilibration, exhibit a similar dependence on base sequence context, and are thus correlated to one another.

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Section: Kinetics Of Dna Oxidation By Co 3 •− Radicalsmentioning

confidence: 99%

Oxidation of Guanine in G, GG, and GGG Sequence Contexts by Aromatic Pyrenyl Radical Cations and Carbonate Radical Anions: Relationship between Kinetics and Distribution of Alkali-Labile Lesions

et al. 2008

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“…Moreover, the oxidation of dGTP would increase under the oxidative stress produced by the exposure to H 2 O 2 in mutT cells. G is highly susceptible to oxidative stress, as it has the lowest redox potential of all four bases [35]. Indeed, the mutation frequency in the mutT cells was one order of magnitude higher than that in the wt cells, when these bacterial cells were treated with We examined the effects of the UvrA-and UvrB-deficiencies on mutations caused by endogenous …”

Section: Reduced Mutation Frequency In Uvra-and Uvrb-deficient Mutt Smentioning

confidence: 99%

UvrA and UvrB enhance mutations induced by oxidized deoxyribonucleotides

et al. 2007

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Oxidatively damaged DNA precursors (deoxyribonucleotides) are formed by reactive oxygen species. After the damaged DNA precursors are incorporated into DNA, they might be removed by DNA repair enzymes. In this study, to examine whether a nucleotide excision repair enzyme, Escherichia coli UvrABC, could suppress the mutations induced by oxidized deoxyribonucleotides in vivo, oxidized DNA precursors, 8-hydroxy-2´-deoxyguanosine 5´-triphosphate and 2-hydroxy-2´-deoxyadenosine 5´-triphosphate, were introduced into uvrA, uvrB, and uvrC E. coli strains, and mutations in the chromosomal rpoB gene were analyzed. Unexpectedly, these oxidized DNA precursors induced mutations only slightly in the uvrA and uvrB strains. In contrast, effect of the uvrC-deficiency was not observed. Next, mutT, mutT/uvrA, and mutT/uvrB E. coli strains were treated with H 2 O 2 , and the rpoB mutant frequencies were calculated. The frequency of the H 2 O 2 -induced mutations was increased in all of the strains tested; however, the increase was threeto four-fold lower in the mutT/uvrA and mutT/uvrB strains than in the mutT strain. Thus, UvrA and UvrB are involved in the enhancement, but not in the suppression, of the mutations induced by these oxidized deoxyribonucleotides. These results suggest a novel role for UvrA and UvrB in the processing of oxidative damage.

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“…18 The E red values of 1a, 2a, and 3a were measured using cyclic voltammetry as shown in Figure S10 of the Supporting Information. Table 4 shows the one-electron redox potentials (vs Ag/AgCl) and the corresponding transition energy, E 0,0 , of dC PPI derivatives.…”

Section: Resultsmentioning

confidence: 99%

Fluorescence Properties of Pyrimidopyrimidoindole Nucleoside dC^PPI Incorporated into Oligodeoxynucleotides

et al. 2009

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A series of oligodeoxynucleotides labeled by a pyrimidopyrimidoindole deoxynucleoside (1a: dC PPI ) and its derivatives 2a and 3a substituted with electron-donating and -withdrawing groups, respectively, were synthesized according to the phosphoramidite approach. The photophysical properties and quenching efficiencies of oligonucleotides incorporating dC PPI derivatives were studied in detail. The thermal denaturation experiments and molecular dynamics simulation of DNA duplexes incorporating dC PPI suggested that a modified base of dC PPI could form base pairs with guanine and adenine in canonical Watson-Crick and reverse-wobble geometries, respectively. The fluorescence of oligonucleotides incorporating dC PPI derivatives increased upon binding to the counter strands, except when dC PPI and guanine formed a base pair. It was revealed that dGMP quenched the fluorescence of the cyano derivative 3a most effectively, whereas it affected that of the methoxy derivative 2a least effectively. The involvement of the electron transfer from guanine to the dC PPI derivatives in the fluorescence quenching was supported by energy considerations.

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How Easily Oxidizable Is DNA? One-Electron Reduction Potentials of Adenosine and Guanosine Radicals in Aqueous Solution

Cited by 1,394 publications

References 25 publications

Oxidation of Guanine in G, GG, and GGG Sequence Contexts by Aromatic Pyrenyl Radical Cations and Carbonate Radical Anions: Relationship between Kinetics and Distribution of Alkali-Labile Lesions

Oxidation of Guanine in G, GG, and GGG Sequence Contexts by Aromatic Pyrenyl Radical Cations and Carbonate Radical Anions: Relationship between Kinetics and Distribution of Alkali-Labile Lesions

UvrA and UvrB enhance mutations induced by oxidized deoxyribonucleotides

Fluorescence Properties of Pyrimidopyrimidoindole Nucleoside dC^PPI Incorporated into Oligodeoxynucleotides

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How Easily Oxidizable Is DNA? One-Electron Reduction Potentials of Adenosine and Guanosine Radicals in Aqueous Solution

Cited by 1,394 publications

References 25 publications

Oxidation of Guanine in G, GG, and GGG Sequence Contexts by Aromatic Pyrenyl Radical Cations and Carbonate Radical Anions: Relationship between Kinetics and Distribution of Alkali-Labile Lesions

Oxidation of Guanine in G, GG, and GGG Sequence Contexts by Aromatic Pyrenyl Radical Cations and Carbonate Radical Anions: Relationship between Kinetics and Distribution of Alkali-Labile Lesions

UvrA and UvrB enhance mutations induced by oxidized deoxyribonucleotides

Fluorescence Properties of Pyrimidopyrimidoindole Nucleoside dCPPI Incorporated into Oligodeoxynucleotides

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Fluorescence Properties of Pyrimidopyrimidoindole Nucleoside dC^PPI Incorporated into Oligodeoxynucleotides