FORMATION OF ALPHA-DEOXYADENOSINE IN POLYDEOXYNUCLEOTIDES EXPOSED TO IONIZING-RADIATION UNDER ANOXIC CONDITIONS

When poly(dA), poly(dA-dT), and salmon testis DNA were γ-irradiated under nitrogen, the major deoxyadenosine damage product (excluding liberated adenine) was identified as the α-anomer of deoxyadenosine. The yields of α-deoxyadenosine from poly(dA), poly(dA-dT), and salmon testis DNA irradiated with a dose of 500 Gy under anoxic conditions were 1.5, 1.3, and 1.3%, respectively. No α-deoxyadenosine was detected after irradiation under oxic conditions. The presence of nucleotides with the α-configuration at the anomeric carbon atom in the DNA chain may have a significant effect on its tertiary structure and possibly modify its biological activity.