Density functional theory studies of electron interaction with DNA: can zero eV electrons induce strand breaks?
The discovery of DNA strand breaks induced by low energy secondary electrons sparks a necessity to elucidate the mechanism. Through theoretical studies based on a sugar-phosphate-sugar model that mimics a backbone section of the DNA strand, it is found that bond cleavages at 3' or 5'C-O sites after addition of an electron are possible with a ca. 10 kcal/mol activation barrier. Moreover, the potential energy surfaces show that dissociation at both sites is highly favorable thermodynamically. Although the phosphate group in DNA is not a favored site for electron attachment because of competitive electron transfer to the bases, any electrons which attach to phosphates on first encounter may induce strand breaks even when the electron energy is near zero eV. These findings have profound implication as low energy secondary electrons are abundantly generated in all types of ionization radiation.
Group of the Canadian Institutes of Health Research in the Radiation Sciences, Faculty of Medicine, Université de Sherbrooke, Quebec, J1H 5N4, Canada.
Xifeng
X
Li
Michael D
MD
Sevilla
Léon
L
Sanche
D004247:DNA / Q000737:chemistry*; D004249:DNA Damage; D003855:Deoxyribose / Q000737:chemistry; D004583:Electrons; D008956:Models, Chemical; D013403:Sugar Phosphates / Q000737:chemistry; D013816:Thermodynamics
D013403:Sugar Phosphates; D003855:Deoxyribose; D004247:DNA