Bothe E, Behrens G, Böhm E, Sethuram B, Schulte-Frohlinde D
Int J Radiat Biol Relat Stud Phys Chem Med. 1986 Jan;49(1):57-66. doi: 10.1080/09553008514552231.
The rate of OH radical-induced strand break formation of single-stranded poly(U) in N2O/O2-saturated aqueous solution was studied by measuring the time-dependence of the electrical conductivity following pulse radiolysis. The first half-life of the total conductivity increase depends slightly on pH and the molecular weight and on the dose per pulse. The activation parameters for strand break formation were found to be EA = 52 kJ mol-1 and A = 5 X 10(8) s-1. Similar first half-lives were observed when the decay of peroxyl radicals of poly(U) was measured by e.s.r. under various conditions. This indicates that poly(U)-peroxyl radicals are involved in the rate-determining step of strand break formation. After pulse radiolysis, strand break formation can be inhibited by the addition of dithiothreitol (DTT) in a rapid-mix apparatus. It is postulated that peroxyl radicals of poly(U) react with DTT by formation of hydroperoxides, thereby preventing strand breakage.
通过测量脉冲辐解后电导率随时间的变化，研究了在N₂O/O₂饱和水溶液中，羟基自由基诱导的单链聚尿苷酸（poly(U)）链断裂形成的速率。总电导率增加的第一个半衰期略微依赖于pH值、分子量以及每脉冲的剂量。发现链断裂形成的活化参数为EA = 52 kJ mol⁻¹，A = 5×10⁸ s⁻¹。在各种条件下，通过电子自旋共振（e.s.r.）测量聚尿苷酸过氧自由基的衰减时，观察到了相似的第一个半衰期。这表明聚尿苷酸过氧自由基参与了链断裂形成的速率决定步骤。脉冲辐解后，在快速混合装置中加入二硫苏糖醇（DTT）可抑制链断裂的形成。据推测，聚尿苷酸的过氧自由基通过形成氢过氧化物与DTT反应，从而防止链断裂。
