Development of a method for measuring degree of dispersion of lesions on radiation-damaged DNA by application of quenching phenomena of fluorescence

Akamatsu, Ken; Shikazono, Naoya

Clustered damage site, that is a DNA region with multiple lesions within a few helical turns, is believed to hardly be repaired. This type of damage is considered to be induced around high-LET radiation tracks and at track-end of secondary electron. However, details of the clustered damage sites are not known. We have developed an analytical method for measuring the degree of dispersion of distances between DNA lesions using fluorescence resonance energy transfer (FRET). Complementary two single-strand DNA with an AP (apurinic/apyrimidinic)-site at each center nucleotide were synthesized. As a result, FRET occurred by anealing these strands. D-A distance calculated from the FRET efficiency was 4 nm, which was reasonable with the estimated one taking the diameter of B-form DNA duplex and length of each probe into account. Now we have tried to apply the FRET method to plasmid DNA irradiated with some radiation qualities. The results and the perspective will be discussed.