Held K D, Synek R W, Powers E L
Int J Radiat Biol Relat Stud Phys Chem Med. 1978 Apr;33(4):317-24. doi: 10.1080/09553007814550231.
Biologically active DNA isolated from Bacillus subtilis was exposed in vitro to X-rays at a concentration of 10 microgram/ml in 29 mM phosphate buffer. Radiation-induced damage to the DNA was quantitatively determined by measuring the decrease in its transforming activity (try2 locus) using B. subtilis 168M (try-) as recipient. In O2, which removes .H and eaq-, the radiation sensitivity of the DNA is less than that in N2-saturated water. In N2O, which has been shown to increase yields of .OH in irardiated aqueous solutions, the radiation sensitivity of Transforming DNA is twice that observed in O2 and 1.5 times that in N2. Addition of 5 X 10(-2) M ethanol or 1.7 X 10(-1) M t-butanol, both .OH scavengers, causes large (about tenfold) reduction in the radiation sensitivity in all three saturating gases. These results suggest the importance of the .OH radical in the loss of biological activity of DNA.
从枯草芽孢杆菌中分离出的具有生物活性的DNA，在体外于29 mM磷酸盐缓冲液中以10微克/毫升的浓度接受X射线照射。通过使用枯草芽孢杆菌168M（try-）作为受体，测量其转化活性（try2位点）的降低来定量确定辐射对DNA造成的损伤。在能去除.H和水合电子（eaq-）的O2中，DNA的辐射敏感性低于在氮气饱和水中的情况。在已被证明能增加辐照水溶液中.OH产率的N2O中，转化DNA的辐射敏感性是在O2中观察到的两倍，是在N2中的1.5倍。添加5×10（-2）M乙醇或1.7×10（-1）M叔丁醇，这两种都是.OH清除剂，会使在所有三种饱和气体中的辐射敏感性大幅降低（约十倍）。这些结果表明.OH自由基在DNA生物活性丧失中具有重要作用。
