Charge-Migration Phenomena in γ-Irradiated Costacking Complexes of DNA Nucleotides: II. An ESR Study of Various Complexes in Frozen Solution

Gregoli, Silvano; Olast, Martial; Bertinchamps, Albert

doi:10.2307/3575154

Cited by 39 publications

(10 citation statements)

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“…The occurrence of charge-migration phenomena in DNA has been the subject of intense debate among radiation chemists. Most of the data obtained by different techniques, namely lowtemperature electron paramagnetic resonance (Gregoli et al, 1979;O'Neill and Fielden, 1994;Becker and Sevilla, 1993;Malone et al, 1994), optical spectroscopy in solutions (Candeias et al, 1992;Candeias and Steenken, 1993;Melvin et al 1996), and biochemical analysis (Croke et al, 1988;Melvin et al, 1995) are consistent with the occurrence of electron migration although the distance and mechanism of migration remain a matter of much controversy. More recently, long-range hole migration through the DNA p-stack and trapping by guanines has been suggested to occur on the basis of type 1 interactions of covalently bound intercalators or modified DNA bases.…”

Section: Introductionmentioning

confidence: 89%

Origin of the Heterogeneous Distribution of the Yield of Guanyl Radical in UV Laser Photolyzed DNA

Angelov¹,

Beylot

Spassky

2005

Biophysical Journal

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Oxidative guanine lesions were analyzed, at the nucleotide level, within DNA exposed to nanosecond ultraviolet (266 nm) laser pulses of variable intensity (0.002-0.1 J/cm 2). Experiments were carried out, at room temperature, in TE buffer (20 mM Tris-HCl, pH 7.5; 1 mM EDTA) containing 35 mM NaCl, on 59-end radioactively labeled double-stranded and singlestranded oligomer DNA at a size of 33-37 nucleobases. Lesions were analyzed on polyacrylamide gel electrophoresis by taking advantage of the specific removal of 8-oxodG from DNA by the formamidopyrimidine DNA glycosylase (Fpg protein) and of the differential sensitivity of 8-oxodG and oxazolone to piperidine. The quantum yields of lesions at individual sites, determined from the normalized intensities of bands, were plotted against the irradiation energy levels. Simplified model fitting of the experimental data enabled to evaluate the spectroscopic parameters characterizing excitation and photoionization processes. Results show that the distribution of guanine residues, excited to the lowest triplet state or photoionized, is heterogeneous and depends on the primary and secondary DNA structure. These findings are generalized in terms of excitation energy and charge-migration mediated biphotonic ionization. On the basis of the changes in the yield of the guanyl radical resulting from local helical perturbations in the DNA p-stack, it can be assessed that the distance range of migration is ,6-8 bp.

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Section: Introductionmentioning

confidence: 89%

Origin of the Heterogeneous Distribution of the Yield of Guanyl Radical in UV Laser Photolyzed DNA

Angelov¹,

Beylot

Spassky

2005

Biophysical Journal

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“…This is most likely because the sugar radicals are neutral in charge and the lost proton is displaced a larger distance. It is well known that base-centered electrons and holes are able to transfer between bases (17)(18)(19)(20)(21)(22). As a result, the efficiency of accumulation of radicals on the bases is somewhat diminished by the electron/hole mobility between stacked bases.…”

Section: Dose Saturationmentioning

confidence: 99%

Electron Paramagnetic Resonance Evidence for a C3′ Sugar Radical in Crystalline d(CTCTCGAGAG) X-Irradiated at 4 K

Debije

Bernhard

2001

Radiation Research

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Debije, M. G. and Bernhard, W. A. Electron Paramagnetic Resonance Evidence for a C3' Sugar Radical in Crystalline d(CTCTCGAGAG) X-Irradiated at 4 K. Radiat. Res. 155, 687-692 (2001). A neutral sugar radical formed by the net loss of hydrogen from C3' has been identified in crystalline DNA X-irradiated at 4 K. Crystals of duplex d(CTCTCGAGAG), known to be of B conformation, were studied using electron paramagnetic resonance (EPR) spectroscopy. The C3' radical was identified by using information from dose saturation, power saturation, thermal annealing, and spectrum simulation. The yield of the C3' radical, G(C3'), is 0.03 +/- 0.01 micromol/J, and its concentration does not appear to saturate up to at least 100 kGy. In the region in which total radical concentration increases linearly with dose, the C3' radical makes up about 4.5% of the total radical population trapped in the oligodeoxynucleotide crystal at 4 K. Based on free base release measured in other oligodeoxynucleotides, we suggest that in d(CTCTCGAGAG) the C3' radical is responsible for about one-third of the strand breakage events.

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“…On the basis of electron paramagnetic resonance (EPR) analysis of radicals formed and stabilized at reduced temperatures in irradiated oriented DNA fibres (Graslund et al 1975, frozen DNA solutions (Gregoli et al . 1982) and co-stacking complexes of DNA nucleotides (Gregoli et al 1979), it has been suggested that specific electron-gain and electron-loss centres are formed . The former are proposed to be stabilized preferentially on thymine and/or cytosine (Bernhard 1989) and the latter on guanine .…”

Section: Introductionmentioning

confidence: 99%

Long-range Hole Migration in Irradiated Crystals of Nucleic Acid Bases. An EPR Study

Herak¹,

Hüttermann²

1991

International Journal of Radiation Biology

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Polycrystalline samples of several nucleic acid bases co-crystallized with small amounts of thioanalogues as impurities were X-irradiated at 77 K and investigated by electron paramagnetic resonance (EPR) spectroscopy for sulphur (S)-centered radicals. Anhydrous cytosine, cytosine monohydrate and cytosine hydrochloride with 0.01-1% incorporated thiocytosine gave strong EPR signals characteristic of S-centered radicals, with spectroscopic parameters different from those for irradiated thiocytosine alone. Likewise, in guanine hydrochloride doped with thioguanine (0.1-1%), strong signals of the radicals associated with thioguanine were observed. For the thymine-thiothymine systems (anhydrous and monohydrate) no characteristic S-centered radicals were observed after the same treatment. This was also the case for samples from non-matching bases and thiols (e.g. cytosine-thioguanine or guanine-thiocytosine), for combinations in the form of frozen glasses or frozen aqueous solutions and for almost all freeze-dried samples composed of the bases containing a small amount of thioanalogues. These observations are discussed in terms of the long-range migration of holes within the stacked base systems.

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Charge-Migration Phenomena in γ-Irradiated Costacking Complexes of DNA Nucleotides: II. An ESR Study of Various Complexes in Frozen Solution

Cited by 39 publications

References 0 publications

Origin of the Heterogeneous Distribution of the Yield of Guanyl Radical in UV Laser Photolyzed DNA

Origin of the Heterogeneous Distribution of the Yield of Guanyl Radical in UV Laser Photolyzed DNA

Electron Paramagnetic Resonance Evidence for a C3′ Sugar Radical in Crystalline d(CTCTCGAGAG) X-Irradiated at 4 K

Long-range Hole Migration in Irradiated Crystals of Nucleic Acid Bases. An EPR Study

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