title: Molecular mechanisms of radiation induced DNA damage: H-addition to bases, direct ionization and double strand break.
abstract: Structures and properties of G.(-H) and of TH. were obtained from quantum mechanical calculations. New AMBER parameters for these radicals were obtained to fit their structures and charge distributions. Molecular mechanics simulations of the conformational changes induced in a 12-mer of DNA, d(CGCGAATTCGCG), by these radicals show that the distances between the base and the C2' of the sugar becomes shorter. Such changes suggest that the base radical can abstract the H2' and transfer the radical from the base to the sugar. Once the radical becomes centered on the sugar a strand break can follow. A simultaneous formation of guanine and thymine radicals on opposite strands may lead to a double strand break.
authors.affiliation: Department of Physiology and Biophysics, Mount Sinai School of Medicine, City University of New York, N.Y. 10029.
authors.forename: R
authors.initials: R
authors.lastname: Osman
authors.forename: L
authors.initials: L
authors.lastname: Pardo
authors.forename: J
authors.initials: J
authors.lastname: Banfelder
authors.forename: A P
authors.initials: AP
authors.lastname: Mazurek
authors.forename: L
authors.initials: L
authors.lastname: Shvartzman
authors.forename: R
authors.initials: R
authors.lastname: Strauss
authors.forename: H
authors.initials: H
authors.lastname: Weinstein
mesh_terms: D001483:Base Sequence; D002241:Carbohydrates / Q000737:chemistry; D004247:DNA / Q000737:chemistry / Q000528:radiation effects*; D004249:DNA Damage / Q000502:physiology*; D003854:Deoxyribonucleotides / Q000737:chemistry*; D005609:Free Radicals; D006859:Hydrogen / Q000737:chemistry*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011839:Radiation, Ionizing
chemical_list: D002241:Carbohydrates; D003854:Deoxyribonucleotides; D005609:Free Radicals; D006859:Hydrogen; D004247:DNA