Migration of radiation damage in DNA

To date, the majority of the studies on radiation-induced migration of damage in DNA at 295 K have concentrated on the ejected electron. It is equally important to know whether hole migration occurs in DNA at room temperature and the distance over which it occurs. More recently the authors have used the approach based upon the ability of 193 nm light to ionize DNA and associated model compounds in an aqueous environment to assess whether hole migration occurs at 295 K. In this short review they will present some of their preliminary indications on hole migration induced by 193 nm light in specifically designed oligodeoxynucleotides. The time resolved technique of flash photolysis of these oligonucleotides with 193 nm light has been described in detail. The solutions are generally saturated with oxygen in order to remove the ejected electrons. The resulting superoxide anion is essentially transparent at > 300 nm and is assumed to be inert at times < 100 s. At present, the oligodeoxynucleotides are generally in the range 0.04--0.08, depending on the base composition of the samples