Radiation damage to deoxyadenosine in solutions of double stranded poly(dA . T)

When the dimers, dApT and TpdA, were irradiated in solution, the type and distribution of the damage products were different. Because this observation was probably due to stereochemical effects, the type and distribution of damage in double stranded DNA might be quite different from those observed when nucleosides and nucleotides were irradiated. In this study, solutions of ds poly(dA . T) were irradiated with 500 Gy, and the damage products analyzed by HPLC after digestion to nucleosides. In N/sub 2/ saturated solutions only the R isomer of 8,5'-cyclodeoxy-adenosine was detected. Moreover, a compound formed in a quantity similar to that of the cyclo derivative after irradiation of dAdo and dAMP solutions was now observed in a quantity 10 times that of the cyclo derivative. These results suggest that model studies with deoxynucleosides and deoxynucleotides should be cautiously extrapolated to cellular DNA