Tu C P, Cohen S N
Gene. 1980 Jul;10(2):177-83. doi: 10.1016/0378-1119(80)90135-3.
Cordycepin-5'-triphosphate (3'-deoxyadenosine-5'-triphosphate) can be incorporated into the 3'-ends of DNA fragments using terminal deoxynucleotidyl transferase from calf thymus (Bollum, 1974). Because cordycepin-5'-monophosphate lacks a 3'-OH group, only a single residue is incorporated. Furthermore, DNA molecules that contain cordycepin-5'-monophosphate at their 3'-ends become resistant to hydrolysis by exonucleases that require free 3'-OH ends. As an alternative to 5'-end labeling of complementary DNA strands, we have used [32P]cordycepin-5'-triphosphate labeling of 3'-ends to confirm the nucleotide sequence of a HhaI-endonuclease-generated pTU4-plasmid DNA fragment that contains several hot spots for insertions of the transposable genetic element Tn3. 3'-End labeling with [32P] cordycepin-5'-triphosphate has also proved useful in determining the sequence of the pTU4 DNA in the vicinity of a strategically located SstII endonuclease cleavage site in the replication region of the plasmid.
虫草素-5'-三磷酸（3'-脱氧腺苷-5'-三磷酸）可利用来自小牛胸腺的末端脱氧核苷酸转移酶（博勒姆，1974年）掺入DNA片段的3'末端。由于虫草素-5'-单磷酸缺乏3'-OH基团，所以只能掺入单个残基。此外，在其3'末端含有虫草素-5'-单磷酸的DNA分子对需要游离3'-OH末端的核酸外切酶的水解具有抗性。作为对互补DNA链5'末端标记的替代方法，我们使用[32P]虫草素-5'-三磷酸对3'末端进行标记，以确认由HhaI内切酶产生的包含转座遗传元件Tn3插入的几个热点的pTU4-质粒DNA片段的核苷酸序列。用[32P]虫草素-5'-三磷酸进行3'末端标记在确定质粒复制区域中一个战略定位的SstII内切酶切割位点附近的pTU4 DNA序列方面也已证明是有用的。
