Held K D, Harrop H A, Michael B D
Int J Radiat Biol Relat Stud Phys Chem Med. 1981 Dec;40(6):613-22. doi: 10.1080/09553008114551601.
The actions and interactions of oxygen and the sulphydryl-containing compound dithiothreitol (DTT) upon the radiation sensitivity of the biological activity of purified Bacillus subtilis transforming DNA have been examined. It has previously been shown that the sensitivity of transforming DNA irradiated in dilute solution is less when irradiation is performed in 100 per cent O2 than when in 100 per cent N2, i.e. O2 protects transforming DNA with a dose-modifying factor of about 0.7. DTT protects transforming DNA in a manner that is dependent on DTT concentration and on gassing conditions. In O2 the DTT protection can largely be attributed to the scavenging of .OH radicals by the DTT, but in anoxia DTT exerts a further protective effect which results in an increasing oxygen enhancement ratio (o.e.r.) with increasing DDT concentration to a maximum o.e.r. of about 14 at 2-5 mM DTT. This additional protective effect of DTT is attributable to hydrogen atom donation from DTT to DNA radicals, thus chemically repairing the DNA. Oxygen appears to block this chemical repair reaction.
研究了氧气和含巯基化合物二硫苏糖醇（DTT）对纯化的枯草芽孢杆菌转化DNA生物活性辐射敏感性的作用及相互作用。此前已经表明，在稀溶液中辐照时，在100%氧气中进行辐照时，转化DNA的敏感性低于在100%氮气中，即氧气以约0.7的剂量修正因子保护转化DNA。DTT以依赖于DTT浓度和通气条件的方式保护转化DNA。在氧气中，DTT的保护作用很大程度上可归因于DTT对·OH自由基的清除，但在缺氧条件下，DTT会发挥进一步的保护作用，导致随着DTT浓度增加，氧增强比（o.e.r.）增加，在2 - 5 mM DTT时最大o.e.r.约为14。DTT的这种额外保护作用归因于DTT向DNA自由基提供氢原子，从而对DNA进行化学修复。氧气似乎会阻断这种化学修复反应。
