Characterization of lesions induced in linear-formed plasmid DNA by valence ionization and Auger decay at carbon, nitrogen and oxygen

Akamatsu, Ken; Fujii, Kentaro; Yokoya, Akinari

The aim of this study is to clarify the difference of DNA damage induced by USX from that by Co-60 -rays. We have recently attended to unaltered base release, strand break terminus and base lesion, focusing on the effect of nitrogen and oxygen K-shell electron ionization. The yields of unaltered bases released were determined by HPLC. To quantify and characterize the strand break termini, the digestion rates of the irradiated DNA pretreated with or without calf intestinal alkaline phosphatase by snake venom phosphodiesterase (SVPD) were measured. This experimental method revealed that the production of the termini, which can not be digested by SVPD, were predominant in comparison with that of SVPD- digestive ones, e.g., with 3'OH, in both USX and -rays. Furthermore, piperidine-treated irradiated DNA was also analyzed by the same method above to quantify piperidine-labile base lesions.