Strand Break Formation in Plasmid DNA Irradiated in Aqueous Solution : Effect of Medium Temperature and Hydroxyl Radical Scavenger Concentration

概要

論文の詳細を見る
Plasmid pBR322 DNA (4363 base pairs) in aerobic aqueous solution was irradiated with ^<60>Co γ-radiation. The change of diffusion coefficients (D) of chemical species, rate constants (k) of radical-DNA interaction and solubilities of O_2 in water cannot be ignored when a temperature varies more than a few tens of centigrade. It is important to examine the variation of the yields of DNA strand breaks as a function of temperature in order to analyze the mechanisms of DNA strand breaks from the chemical point of view. Hence, we observed the change of the yield of strand breaks with temperatures between -20 and 42t by agarose gel electrophoresis. We also observed the change of the yield of strand breaks with the concentra-tion of OH scavenger (Tris) from 1 mmol dm^3 to 100 mmol dm^3 and summarized it with previous experiments. This summarization indicated that the order of the lifetime of OH radical in cellular environment is several nanosecond. This value is consistent with the measurement of the lifetime of 8.7 nanosecond for OH radical in mammalian cell (Roots, R. and Okada, S. (1975) Radiat. Res. 64, 306-320).
日本放射線影響学会の論文