Radiation-induced DNA strand breaks in deoxygenated aqueous solutions. The formation of altered sugars as end groups.

Gamma irradiation of DNA in deoxygenated, N2O-saturated aqueous solution leads to three bound altered sugars present as end groups in broken DNA strands. These sugars are linked to the DNA by phosphoric acid ester bonds. Two of the end groups have the structures (4) and (5). (Formula: see text) The third end group after dephosphorylation has structure (3). The formation of the bound sugars (4) and (5) is explained by a mechanism postulated earlier for the formation of free altered sugars. Except for the phosphoric acid ester linkage, the free altered sugars have the same chemical structures as the bound altered sugars.