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Title: DNA strand breaks induced by concerted interaction of H radicals and low-energy electrons. A computational study of the nucleotide of cytosine

Abstract

We propose a mechanism of DNA single strand breaks induced by low-energy electrons. Density functional theory calculations have been performed on a nucleotide of cytosine to identify barriers for the phosphate-sugar O-C bond cleavage. Attachment of the first excess electron induces intermolecular proton transfer to cytosine. The resulting neutral radical of hydrogenated cytosine binds another excess electron, and the excess charge is localized primarily on the C6 atom. A barrier based of free enthalpies of 4.2 kcal/mol is encountered for proton transfer from the C2’ atom of the adjacent sugar unit to the C6 atom of cytosine. The proton transfer is followed by a barrier-free sugar-phosphate C-O bond cleavage. The rate of the C-O bond cleavage in the anion of hydrogenated nucleotide of cytosine is estimated to be in a range 5x108 to 2x1010 s-1, which makes the proposed mechanism probable to take place in DNA. The process proceeds through bound anionic states, not through metastable states with finite lifetimes and discrete energy positions with respect to the neutral target. The results suggest that even very low-energy electrons may cleave the DNA backbon

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
15020813
Report Number(s):
PNNL-SA-43658
KP1102020; TRN: US0504730
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Journal Name:
European Physical Journal. D, Atomic, molecular and optical physics., 35(2):429-435
Additional Journal Information:
Journal Volume: 35; Journal Issue: 2
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; ANIONS; ATOMS; CLEAVAGE; CYTOSINE; DNA; ELECTRONS; FUNCTIONALS; METASTABLE STATES; NUCLEOTIDES; PROTONS; RADICALS; SACCHAROSE; STRAND BREAKS; electrons; cytosine

Citation Formats

Dabkowska, Iwona, Rak, Janusz, and Gutowski, Maciej S. DNA strand breaks induced by concerted interaction of H radicals and low-energy electrons. A computational study of the nucleotide of cytosine. United States: N. p., 2005. Web.
Dabkowska, Iwona, Rak, Janusz, & Gutowski, Maciej S. DNA strand breaks induced by concerted interaction of H radicals and low-energy electrons. A computational study of the nucleotide of cytosine. United States.
Dabkowska, Iwona, Rak, Janusz, and Gutowski, Maciej S. 2005. "DNA strand breaks induced by concerted interaction of H radicals and low-energy electrons. A computational study of the nucleotide of cytosine". United States.
@article{osti_15020813,
title = {DNA strand breaks induced by concerted interaction of H radicals and low-energy electrons. A computational study of the nucleotide of cytosine},
author = {Dabkowska, Iwona and Rak, Janusz and Gutowski, Maciej S},
abstractNote = {We propose a mechanism of DNA single strand breaks induced by low-energy electrons. Density functional theory calculations have been performed on a nucleotide of cytosine to identify barriers for the phosphate-sugar O-C bond cleavage. Attachment of the first excess electron induces intermolecular proton transfer to cytosine. The resulting neutral radical of hydrogenated cytosine binds another excess electron, and the excess charge is localized primarily on the C6 atom. A barrier based of free enthalpies of 4.2 kcal/mol is encountered for proton transfer from the C2’ atom of the adjacent sugar unit to the C6 atom of cytosine. The proton transfer is followed by a barrier-free sugar-phosphate C-O bond cleavage. The rate of the C-O bond cleavage in the anion of hydrogenated nucleotide of cytosine is estimated to be in a range 5x108 to 2x1010 s-1, which makes the proposed mechanism probable to take place in DNA. The process proceeds through bound anionic states, not through metastable states with finite lifetimes and discrete energy positions with respect to the neutral target. The results suggest that even very low-energy electrons may cleave the DNA backbon},
doi = {},
url = {https://www.osti.gov/biblio/15020813}, journal = {European Physical Journal. D, Atomic, molecular and optical physics., 35(2):429-435},
number = 2,
volume = 35,
place = {United States},
year = {Mon Aug 01 00:00:00 EDT 2005},
month = {Mon Aug 01 00:00:00 EDT 2005}
}