Andoh T, Ishii K, Suzuki Y, Ikegami Y, Kusunoki Y, Takemoto Y, Okada K
Proc Natl Acad Sci U S A. 1987 Aug;84(16):5565-9. doi: 10.1073/pnas.84.16.5565.
DNA topoisomerase I was purified to near homogeneity from a clonal line of human lymphoblastic leukemia cells, RPMI 8402, that is resistant to camptothecin, a cytotoxic alkaloid from Camptotheca acuminata, and compared with that of the parent wild-type cells. As assayed by relaxation of the supercoiled plasmid DNA and by formation of enzyme-linked DNA breaks, the purified enzyme from the resistant cells was shown to be greater than 125-fold as resistant to camptothecin as the wild-type enzyme, comparable to a cellular resistance index of about 300. Therefore, the cellular resistance appears to be due to the resistance of the enzyme. The amount of the immunoreactive enzyme protein in whole extract appeared to be reduced to less than half that of the wild-type enzyme. These results establish that DNA topoisomerase I is the cellular target of camptothecin and that DNA topoisomerase I is essential for the survival of mammalian cells.
从人淋巴细胞白血病细胞系RPMI 8402（对喜树碱有抗性，喜树碱是一种来自喜树的细胞毒性生物碱）中纯化出接近均一的DNA拓扑异构酶I，并与亲本野生型细胞的该酶进行比较。通过超螺旋质粒DNA的松弛和酶联DNA断裂的形成来检测，结果显示，来自抗性细胞的纯化酶对喜树碱的抗性是野生型酶的125倍以上，与约300的细胞抗性指数相当。因此，细胞抗性似乎是由于该酶的抗性所致。全提取物中免疫反应性酶蛋白的量似乎减少到野生型酶的一半以下。这些结果表明，DNA拓扑异构酶I是喜树碱的细胞靶点，并且DNA拓扑异构酶I对哺乳动物细胞的存活至关重要。
Zotero 插件
