Iodine-125 Decay in a Synthetic Oligodeoxynucleotide. I. Fragment Size Distribution and Evaluation of Breakage Probability
Iodine-125 Decay in a Synthetic Oligodeoxynucleotide. I. Fragment Size Distribution and Evaluation of Breakage Probability
复制标题
合成寡脱氧核苷酸中的碘 125 衰变。
作者：
P. Lobachevsky;R. F. Martin
摘要罗巴切夫斯基，P. N。和Martin，R. F.合成寡脱氧核苷酸中的碘-125衰变。I.碎片尺寸分布和断裂概率评估。将125 I-dC掺入到双链寡脱氧核苷酸的确定位置中用于研究由俄歇电子发射同位素衰变引起的DNA断裂。在含125 I-dC（所谓的顶部）或相对（底部）链的5′或3′端，也用32 P标记寡脱氧核苷酸样品，并在4°C下在20 mM磷酸盐缓冲液或相同缓冲液加2 M二甲亚砜中孵育18-20天。在变性聚丙烯酰胺凝胶上分离由125 I衰变产生的32 P-末端标记的片段，并且在从凝胶洗脱片段后通过闪烁计数确定每个片段中的32 P活性。然后将相对片段大小分布在每次衰变的基础上归一化，并转换为单链断裂概率的分布，作为与125 I-dC的距离的函数。对于标记和孵育条件的八种可能组合中的每一种，三至五次实验的结果以表格形式呈现，该表格显示了不同片段中32 P计数的相对数量以及归一化片段大小分布和断裂概率的图。每125 I衰变的单链断裂的平均数分别为3.3和3.7在顶部链和1.3和1.5在底部链与二甲亚砜，分别。每个125 I衰变事件都会在顶链中产生断裂，并且在75-80%的事件中发生底链的断裂。因此，125 I衰变产生双链断裂的概率约为0.8。
Abstract Lobachevsky, P. N. and Martin, R. F. Iodine-125 Decay in a Synthetic Oligodeoxynucleotide. I. Fragment Size Distribution and Evaluation of Breakage Probability. Incorporation of 125I-dC into a defined location of a double-stranded oligodeoxynucleotide was used to investigate DNA breaks arising from decay of the Auger electron-emitting isotope. Samples of the oligodeoxynucleotide were also labeled with 32P at either the 5′ or 3′ end of either the 125I-dC-containing (so-called top) or opposite (bottom) strand and incubated in 20 mM phosphate buffer or the same buffer plus 2 M dimethylsulfoxide at 4°C during 18–20 days. The 32P-end-labeled fragments produced by 125I decays were separated on denaturing polyacrylamide gels, and the 32P activity in each fragment was determined by scintillation counting after elution of fragments from the gel. The relative fragment size distributions were then normalized on a per decay basis and converted to a distribution of single-strand break probabilities as a function of distance from the 125I-dC. The results of three to five experiments for each of eight possible combinations of labels and incubation conditions are presented as a table showing the relative numbers of 32P counts in different fragments as well as graphs of normalized fragment size distributions and probabilities of breakage. The average numbers of single-strand breaks per 125I decay are 3.3 and 3.7 in the top strand and 1.3 and 1.5 in the bottom strand with and without dimethylsulfoxide, respectively. Every 125I decay event produces a break in the top strand, and breakage of the bottom strand occurs in 75–80% of the events. Thus a double-strand break is produced by 125I decay with a probability of approximately 0.8.
125I 的低 LET 和高 LET 辐射作用在 DNA 中衰减：半胱胺对微核形成和细胞杀伤的影响。
DOI：
--
发表时间：
1995
期刊：
Radiation research.
影响因子：
--
作者：
Hofer,KG;Bao,SP
通讯作者：
Bao,SP
影响因子：
56.9
作者：
MARTIN, RF;HASELTINE, WA
通讯作者：
HASELTINE, WA