Single- and double-strand breaks in solid pBR322 DNA induced by ultrasoft X-rays at photon energies of 388, 435 and 573 eV.

摘要: We measured strand breaks of pBR322 plasmid DNA irradiated with ultrasoft X-rays using monochromatic synchrotron radiation as a light source. Three photon energies, 388, 435 and 573 eV, value below above the nitrogen K-edge oxygen K-edge, respectively, were chosen for irradiation experiments they have an equivalent transmittance sample. Irradiated was analyzed by agarose gel electrophoresis numbers single- double-strand (ssb dsb) determined measuring band intensity on after ethidium bromide staining. The action cross-sections ssb dsb slightly increased energy. ratio between 388 eV about 1.5 both forms breaks. absorbed energy required break 60 1 keV dsb, less than one fifth values obtained previously in 2 region. On other hand, energies per break, well cross-section to that constant regardless used. K-shell photoabsorption carbon, atoms molecule, followed Auger cascade, induced efficiency terms These results indicate molecule solid state are mainly caused photo- Auger-electrons little depends ejecting these secondary electrons.