Mechanisms of Direct Radiation Damage in DNA, Based on a Study of the Yields of Base Damage, Deoxyribose Damage, and Trapped Radicals in d(GCACGCGTGC)2

Abstract Swarts, S. G., Gilbert, D. C., Sharma, K. K., Razskazovskiy, Y., Purkayastha, S., Naumenko, K. A. and Bernhard, W. A. Mechanisms of Direct Radiation Damage in DNA, Based on a Study of the Yields of Base Damage, Deoxyribose Damage, and Trapped Radicals in d(GCACGCGTGC)2. Radiat. Res. 168, 367–381 (2007). Dose–response curves were measured for the formation of direct-type DNA products in X-irradiated d(GCACGCGTGC)2prepared as dry films and as crystalline powders. Damage to deoxyribose (dRib) was assessed by HPLC measurements of strand break products containing 3′ or 5′ terminal phosphate and free base release. Base damage was measured using GC/ MS after acid hydrolysis and trimethylsilylation. The yield of trappable radicals was measured at 4 K by EPR of films X-irradiated at 4 K. With exception of those used for EPR, all samples were X-irradiated at room temperature. There was no measurable difference between working under oxygen or under nitrogen. The chemical yields (in units of nmol/J) for trap...