Ralph R K, Hancock R
Can J Biochem Cell Biol. 1985 Jul;63(7):780-3. doi: 10.1139/o85-099.
A 175 kdalton (kDa) polypeptide is bound covalently to the chromosomal DNA fragments from mouse cells exposed to the intercalating agent 4'-[(9-acridinyl)-amino]methansulphon-m-anisidide. Electron microscopy shows a terminal protein on the DNA fragments, whose 5'-termini are blocked. Since the relative molecular mass of topoisomerase II polypeptide chains is also about 175 kDa and topoisomerase II inhibitors prevent intercalator-induced DNA fragmentation, we propose that the polypeptide bound covalently to the 5'-terminus of the DNA fragments is a polypeptide derived from frequently integrated topoisomerase II operating to normalize torsional stress resulting from intercalation.
一种175千道尔顿（kDa）的多肽与暴露于嵌入剂4'-[(9-吖啶基)-氨基]甲磺基间茴香胺的小鼠细胞染色体DNA片段共价结合。电子显微镜显示DNA片段上有一个末端蛋白，其5'-末端被封闭。由于拓扑异构酶II多肽链的相对分子质量也约为175 kDa，且拓扑异构酶II抑制剂可防止嵌入剂诱导的DNA片段化，我们提出与DNA片段5'-末端共价结合的多肽是一种源自频繁整合的拓扑异构酶II的多肽，该酶作用是使嵌入导致的扭转应力正常化。
