Abstract
Structural information about DNA damage site is important to clarify the repair processes. Particularly, the damage induced by ionizing radiations is expected to be multifarious, so this has prevented us to discover the upper stream of the radiation biological effects. Here, we propose a novel method to obtain qualitative information as well as quantitative one using enzyme kinetics. To characterize the cleavage sites, digestion velocity of the irradiated DNA pretreated with or without calf intestinal alkaline phosphatase by snake venom phosphodiesterase (SVPD) was measured. SVPD is an exonuclease producing a deoxynucleoside-5'-monophosphate one after another from a 3'OH terminus. The alkaline phosphatase treatment enables some of the SVPD-resistant sites to be digestive by SVPD. The initial digestion velocity is expected to give us information about the cleavage sites such as the amount, the chemical structure In this presentation, we will discuss variations of DNA cleavage produced by ionizing radiations, suggested by the experiments based on enzyme reaction kinetics.
