title: Strand break induction by photoabsorption in DNA-bound molecules.
abstract: Dried samples of a DNA-chloroterpyridine platinum complex were irradiated with monochromatic X rays tuned to the photoabsorption resonance of the L(III) inner shell of the platinum atom. The number of single- and double-strand breaks (SSBs and DSBs) triggered by the Auger effect in supercoiled DNA plasmids was measured by the production of circular nicked and linear forms. To probe the specific contribution of the L(III) inner-shell excitation of the platinum atom, photon wavelengths were tuned on the resonance energy (on peak) and below (off peak). The quantum yields of the resonance radiation were typically found to be 11 for the SSBs and 1 for the DSBs. The DSB-to-SSB ratio increased by 20% when switching from off-resonance to on-resonance irradiation.
authors.affiliation: Laboratoire des Collisions Atomiques et Moléculaires (URA 281) Bât 351, 91405 Orsay Cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Le Sech
authors.forename: K
authors.initials: K
authors.lastname: Takakura
authors.forename: C
authors.initials: C
authors.lastname: Saint-Marc
authors.forename: H
authors.initials: H
authors.lastname: Frohlich
authors.forename: M
authors.initials: M
authors.lastname: Charlier
authors.forename: N
authors.initials: N
authors.lastname: Usami
authors.forename: K
authors.initials: K
authors.lastname: Kobayashi
mesh_terms: D004247:DNA / Q000528:radiation effects*; D004249:DNA Damage; D004583:Electrons; D014965:X-Rays
chemical_list: D004247:DNA