STRAND BREAK FORMATION IN PLASMID DNA IRRADIATED IN AQUEOUS-SOLUTION - EFFECT OF

2020-03-26 15:40:43

DNA radical Of Strand breaks

责任者: TOMITA, H;KAI, M;KUSAMA, T;AOKI, Y 单位: 来源出处: JOURNAL OF RADIATION RESEARCH, v 36, MAR 1995, p 46- 55 摘要: Plasmid pBR322 DNA (4363 base pairs) in aerobic aqueous solution was irradiated with Co-60 gamma-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 42 degrees C by agarose gel electrophoresis. We also observed the change of the yield of strand breaks with the concentration 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). 关键词: PLASMID DNA; STRAND BREAK; AQUEOUS SOLUTION; TEMPERATURE; LIFETIME OF HYDROXYL RADICAL HYDROXYL RADICAL; IONIZING-RADIATION; SINGLE-STRAND; FAST-NEUTRONS; DEPENDENCE; WATER; RADIOLYSIS; DAMAGE; OXYGEN; THIOLS; REPAIR RADIOLYSIS; DAMAGE; OXYGEN; THIOLS; REPAIR