Photolysis of polycytidylic acid on 193 nm laser excitation

Görner, Helmut; Gurzadyan, Gagik G.

doi:10.1016/1010-6030(93)85067-i

Cited by 12 publications

(9 citation statements)

References 25 publications

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“…The chemical and biological effects of UV radiation on purine and pyrimidine nucleosides and nucleotides have been the subject of many studies (1)(2)(3). Among the different primary photochemical processes, photoionization (PI) of nucleotides and nucleosides plays an important role in the damage to DNA or RNA caused by high-energy UV radiation (4)(5)(6). In PI the resulting transient species are the hydrated electron and the base radical cation, which subsequently deprotonates or reacts with water molecules to form stable ¶Posted on the web site on 20 June 2002.…”

Section: Introductionmentioning

confidence: 99%

Photoionization of DNA and RNA Bases, Nucleosides and Nucleotides Through a Combination of One- and Two-photon Pathways upon 266 nm Nanosecond Laser Excitation¶

Crespo‐Hernández

Arce

2002

Photochem Photobiol

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The 266 nm nanosecond laser photolysis of various purine and pyrimidine derivatives results in their photoionization (PI) as one of the primary photochemical pathways. Electron photoejection occurs through a combination of one- and two-photon mechanisms. The PI values depend on the substituents attached to the chromophore of the base. The net PI of the purine bases at 266 nm are of the same order of magnitude (10(-2)) as those of the pyrimidine bases under similar experimental conditions. The monophotonic component is approximately one-third of the net PI yield of the bases. A nonrelaxed singlet excited state intermediate is tentatively proposed for this pathway. It is proposed that this state is significantly stabilized by water solvation, transforming it into a charge transfer to solvent state from which the hydrated electron evolves.

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Section: Introductionmentioning

confidence: 99%

Photoionization of DNA and RNA Bases, Nucleosides and Nucleotides Through a Combination of One- and Two-photon Pathways upon 266 nm Nanosecond Laser Excitation¶

Crespo‐Hernández

Arce

2002

Photochem Photobiol

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“…Radiation and low-energy electrons often induce DNA damage that leads to strand breaks, mutations, photolesions, transcription errors, and cancer. − To elucidate the underlying DNA oxidative damage mechanisms, the electronic structure and ionization potentials of DNA building blocks are much needed. Because DNA is a polymer built of four nucleotides, each composed of a nucleobase [adenine (A), guanine (G), cytosine (C), or thymine (T)], a deoxyribose residue, and a phosphate group, an effective approach for studying this huge molecule would be a variant of a reductionistic method, e.g., an application of gas-phase spectroscopy on isolated nucleotides.…”

mentioning

confidence: 99%

Photoelectron Spectroscopy and Theoretical Investigations of Gaseous Doubly Deprotonated 2′-Deoxynucleoside 5′-Monophosphate Dianions

Yuan

Chomicz-Mańka

Makurat

et al. 2021

J. Phys. Chem. Lett.

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A better understanding of the mechanism of oxidative DNA damage requires obtaining a molecular level description of nucleotides in various charge states. Herein, we report a systematic photoelectron spectroscopy and theoretical investigation of the electronic and geometric structures of four doubly deprotonated 2′-deoxynucleoside 5′-monophosphate dianions, the smallest quintessential DNA building block. These dianions are intrinsically stable with their adiabatic/vertical detachment energies (ADE/VDE) ranging from 0.85/1.07 (A) and 1.05/1.30 (G) to 1.20/1.50 (C) and 1.80/2.10 eV (T). The repulsive Coulomb barrier against electron detachment is 2.0 eV for purines and 2.5 eV for pyrimidines. Dianions are deprotonated at the phosphate group and the amino group of a nucleobase. The πtype HOMO orbital resides on the nucleobase moiety for each dianion. This spatial distribution of HOMO suggests that the most loosely bound electron is detached along the direction perpendicular to the nucleobase. When combined with the previous results, this work makes complete the depiction of basic building blocks of DNA at the molecular level.

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“…In 0,-saturated solution the dependencies of the concentration of free bases vs dose (at conversions of up to 5-10%) are linear in all cases ( Figs. 1-4), except for poly(C), where photodecomposition of both bound and free cytosine occurs in relative high quantum yield (Gorner and Gurzadyan, 1992). This initial linearity and the rather similar QB values under Ar and O2 (Tables 1 and 2) indicate that a contribution of O$ produced from e;, under oxygen to base release is unimportant.…”

Section: Effect Of Oxygenmentioning

confidence: 76%

“…4), the cytosine concentration from poly(C) reaches a maximum at a dose of about 1.5 J cm-2 and decreases at higher doses. The reason for this dependence is photodecomposition of both free and bound cytosine; results related to chromophore loss upon 193 nm excitation will be presented elsewhere (Gorner and Gurzadyan, 1992). We therefore measured Qc only under conditions of low (<lo%) conversion, using a significantly larger polynucleotide concentration ( Table 2).…”

Section: Quantum Yields Of Base Release In Dnamentioning

confidence: 99%

BASE RELEASE FROM DNA AND POLYNUCLEOTIDES UPON 193 nm LASER EXCITATION

Gurzadyan

Görner

1992

Photochem & Photobiology

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Release of bases form calf thymus DNA and three polynucleotides, induced by 20 ns excitation at 193 nm in aqueous solution at pH 7, was detected by HPLC. The quantum yields of formation of free bases (phi B) from double-stranded DNA (0.4 mM) are independent of intensity, indicating a one-quantum mechanism of N-glycosidic bond cleavage. The phi B values increase in the order guanine, thymine, adenine, cytosine, the latter being phi C approximately 7 x 10(-4) for double-stranded DNA under Ar and O2. The larger phi B values in N2O-saturated solution, e.g., phi C = 1.2 x 10(-3), are ascribed to additional base release via OH-adduct radicals. The phi B values of homopolynucleotides increase in the order poly(G), poly(A) and poly(C), e.g. phi C = 7 x 10(-3) under Ar, as do the efficiencies for base release per radical cation (eta B). A comparison of the eta B values with the efficiencies of single-strand breakage for poly(C), poly(A) and DNA shows a similar trend; both are markedly larger for pyrimidines than for purines. Pathways to undamaged bases, initiated from base radical cations, are proposed.

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Photolysis of polycytidylic acid on 193 nm laser excitation

Cited by 12 publications

References 25 publications

Photoionization of DNA and RNA Bases, Nucleosides and Nucleotides Through a Combination of One- and Two-photon Pathways upon 266 nm Nanosecond Laser Excitation¶

Photoionization of DNA and RNA Bases, Nucleosides and Nucleotides Through a Combination of One- and Two-photon Pathways upon 266 nm Nanosecond Laser Excitation¶

Photoelectron Spectroscopy and Theoretical Investigations of Gaseous Doubly Deprotonated 2′-Deoxynucleoside 5′-Monophosphate Dianions

BASE RELEASE FROM DNA AND POLYNUCLEOTIDES UPON 193 nm LASER EXCITATION

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