Near 0 eV Electrons Attach to Nucleotides

Gu, Jiande; Xie, Yaoming; Schaefer, Henry F.

doi:10.1021/ja055615g

Cited by 88 publications

(152 citation statements)

References 22 publications

Supporting

Mentioning

145

Contrasting

Unclassified

Order By: Relevance

“…This could be tested in future TPRES experiments by attaching electron-withdrawing substituents to adenine at the N9 position. Work on low-energy electron attachment suggests that electrons attach either to the phosphate P ϭ O * orbital or directly to a * orbital of the nucleobase (39,43). Theoretical considerations show that electron attachment to a * orbital at the nucleobase can lead to rupture of the COO bond between the sugar and the phosphate (39,(44)(45)(46).…”

Section: Resultsmentioning

confidence: 99%

Primary processes underlying the photostability of isolated DNA bases: Adenine

Satzger

Townsend

Zgierski

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

188

238

View full text Add to dashboard Cite

The UV chromophores in DNA are the nucleic bases themselves, and it is their photophysics and photochemistry that govern the intrinsic photostability of DNA. Because stability is related to the conversion of dangerous electronic to less-dangerous vibrational energy, we study ultrafast electronic relaxation processes in the DNA base adenine. We excite adenine, isolated in a molecular beam, to its * state and follow its relaxation dynamics using femtosecond time-resolved photoelectron spectroscopy. To discern which processes are important on which timescales, we compare adenine with 9-methyl adenine. Methylation blocks the site of the much-discussed * state that had been thought, until now, minor. Time-resolved photoelectron spectroscopy reveals that, although adenine and 9-methyl adenine show almost identical timescales for the processes involved, the decay pathways are quite different. Importantly, we confirm that in adenine at 267-nm excitation, the * state plays a major role. We discuss these results in the context of recent experimental and theoretical studies on adenine, proposing a model that accounts for all known results, and consider the relationship between these studies and electron-induced damage in DNA.dynamics ͉ photochemistry H ow did nature protect the genetic code from damage by harmful UV radiation? Presumably, DNA itself must have inherent protection mechanisms that quickly convert dangerous electronic excitation into less-dangerous vibrational energy that subsequently cools rapidly in solution. Unfortunately, the details of these mechanisms remain obscure (1). The main UV chromophores in DNA are the nucleotide bases themselves, and therefore it is their primary photophysics and interactions, both long-and short-range, which underlie DNA photostability. The isolated DNA bases are small enough to attempt detailed quantum chemical calculations, and considerable effort has been devoted to this area (for a recent review, see ref.

show abstract

Section: Resultsmentioning

confidence: 99%

Primary processes underlying the photostability of isolated DNA bases: Adenine

Satzger

Townsend

Zgierski

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

188

238

View full text Add to dashboard Cite

show abstract

“…Bao et al [72,105] calculated the activation energies for bond cleavage in the pyrimidine nucleotides and found that C-O strand breaks should dominate at near-zero energies. By calculating the detachment energies from the base they also showed that it is feasible that electron attachment to the nucleobase can trigger bond cleavage [114]. Barrios et al explored the energy surfaces leading to bond cleavage and also found that C-O cleavage would be operational at such low energies [41,115].…”

Section: From Dea To Thermal Activationmentioning

confidence: 99%

Interactions between low energy electrons and DNA: a perspective from first-principles simulations

Kohanoff¹,

McAllister²,

Tribello³

et al. 2017

J. Phys.: Condens. Matter

View full text Add to dashboard Cite

Abstract. DNA damage caused by irradiation has been studied for many decades. Such studies allow us to better assess the dangers posed by radiation, and to increase the efficiency of the radiotherapies that are used to combat cancer. A full description of the irradiation process involves multiple size and time scales. It starts from the interaction of radiation -either photons or swift ions -with the biological medium. Such interactions cause electronic excitation and ionisation. The two main products of ionising radiation are thus electrons and radicals. Both of these species can cause damage to biological molecules, in particular DNA. In the long run, this molecular level damage can prevent cells from replicating and can hence lead to cell death. For a long time it was assumed that the main actors in the damage process were the radicals. However, experiments in a seminal paper by the group of Leon Sanche in 2000 showed that low-energy electrons (LEE), such as those generated when ionising biological targets, can also cause bond breaks in biomolecules, in particular strand breaks in plasmid DNA [1]. These results prompted a significant amount of experimental and theoretical work aimed at elucidating the role played by LEE in DNA damage.In this Topical Review we provide a general overview of the problem. We discuss experimental findings and theoretical results hand in hand with the aim of describing the physics and chemistry that occurs during the process of radiation damage, from the initial stages of electronic excitation, through the inelastic propagation of electrons in the medium, the interaction of electrons with DNA, and the chemical end-point effects on DNA. A very important aspect of this discussion is the consideration of a realistic, physiological environment. The role played by the aqueous solution and the amino acids from the histones in chromatin must be considered. Moreover, thermal fluctuations must be incorporated when studying these phenomena. Hence, a special place in this Topical Review is occupied by our recent first-principles molecular dynamics simulations that address the issue of how the environment favours or prevents LEEs from causing damage to DNA. We finish by summarising the conclusions achieved so far, and by suggesting a number of possible directions for further study.

show abstract

“…With the reliably calibrated B3LYP/DZP++ approach [94], the electron affinity of 3 -dCMPH (electron attachment to 3 -dCMPH leads to the base-centered radical anion in the first step of the assumed mechanism) has been studied by Schaefer and coworkers [95]. This investigation revealed that 3 -dCMPH was able to capture a near 0 eV electron to form a stable radical anion in both the gas phase and an aqueous solution.…”

Section: Formation Of Single Strand Breaks Via Adiabatically Stable Amentioning

confidence: 99%

Stable Valence Anions of Nucleic Acid Bases and DNA Strand Breaks Induced by Low Energy Electrons

Rak

Mazurkiewicz

Kobyłecka

et al. 2008

Challenges and Advances in Computational Chemistry and Physics

View full text Add to dashboard Cite

Abstract:The last decade has witnessed immense advances in our understanding of the effects of ionizing radiation on biological systems. As the genetic information carrier in biological systems, DNA is the most important species which is prone to damage by high energy photons. Ionizing radiations destroy DNA indirectly by forming low energy electrons (LEEs) as secondary products of the interaction between ionizing radiation and water. An understanding of the mechanism that leads to the formation of single and double strand breaks may be important in guiding the further development of anticancer radiation therapy. In this article we demonstrate the likely involvement of stable nucleobases anions in the formation of DNA strand breaks -a concept which the radiation research community has not focused on so far. In Section 21.1 we discuss the current status of studies related to the interaction between DNA and LEEs. The next section is devoted to the description of proton transfer induced by electron attachment to the complexes between nucleobases and various proton donorsa process leading to the strong stabilization of nucleobases anions. Then, we review our results concerning the anionic binary complexes of nucleobases with particular emphasize on the GC and AT systems. Next, the possible consequences of interactions between DNA and proteins in the context of electron attachment are briefly discussed. Further, we focus on existing proposal of single strand break formation in DNA. Ultimately, open questions as well perspectives of studies on electron induced DNA damage are discussed

show abstract

Near 0 eV Electrons Attach to Nucleotides

Cited by 88 publications

References 22 publications

Primary processes underlying the photostability of isolated DNA bases: Adenine

Primary processes underlying the photostability of isolated DNA bases: Adenine

Interactions between low energy electrons and DNA: a perspective from first-principles simulations

Stable Valence Anions of Nucleic Acid Bases and DNA Strand Breaks Induced by Low Energy Electrons

Contact Info

Product

Resources

About