Analysis of DNA damage spectrum in plasmid exposed to ionizing radiation using phosphodiesterase I function

Akamatsu, Ken

We have developed a new methodology to characterize radiation damage in plasmid DNA without radioisotope labeling. An enzyme system consisting of the 3'-5'exonuclease (phosphodiesterase I) derived from snake venom (SVPD), and calf intestine alkaline phosphatase (CIAP) was used to examine the 3'termini of strand break sites. In this study, we hypothesized that the strand-break termini can be divided into two categories: CIAP-independent SVPD sites and CIAP-dependent SVPD sites. The former consists of strand-break termini that can directly be recognized and digested by SVPD without CIAP pretreatment, whereas the latter includes the termini that cannot be digested by SVPD without CIAP pretreatment. In this presentation, we will DNA damage spectral data for several radiation sources.