title: Low-Energy Electron Interaction with the Phosphate Group in DNA Molecule and the Characteristics of Single-Strand Break Pathways.
abstract: We modeled the low-energy electron attachment to the sugar-phosphate-sugar (SPS) molecule for investigating the single-strand break (3' C-O and 5' C-O) at the DNA backbone. In particular, we predicted the electron capture at the phosphate center. We found that 0.6 eV electron can attach to the phosphate group, and the lifetime (∼40-55 fs) of the resulting temporary negative ion state is more than what we found for the lifetime of the metastable species (∼18-20 fs) formed at the cytosine base center. We treated the two competing dissociation channels in SPS molecule, that is, both the 3' C-O and 5' C-O lesions, separately. The activation energy barrier calculated for 5' C-O bond rupture is found to be less than that for 3' C-O bond dissociation. The overall low-energy electron transfer process is found to be mediated through a "shape resonance state" formed at the phosphate center.
authors.affiliation: Department of Chemistry, Indian Institute of Technology Guwahati , Guwahati 781 039, India.
authors.forename: Renjith
authors.initials: R
authors.lastname: Bhaskaran
authors.affiliation: Department of Chemistry, Indian Institute of Technology Guwahati , Guwahati 781 039, India.
authors.forename: Manabendra
authors.initials: M
authors.lastname: Sarma
mesh_terms: D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D053904:DNA Breaks, Single-Stranded; D004583:Electrons; D004735:Energy Transfer; D008958:Models, Molecular; D010710:Phosphates / Q000737:chemistry*
chemical_list: D010710:Phosphates; D004247:DNA