Filatov M V, Varfolomeeva E Y
St. Petersburg Nuclear Physics Institute, Russia.
Mutat Res. 1995 Mar;327(1-2):209-15. doi: 10.1016/0027-5107(94)00189-c.
The fluorescent dye Hoechst 33342, which binds tightly to DNA in the minor groove, can be effectively extracted from the DNA in vivo due to an energy-dependent process. It is the dissociation of the dye from DNA rather than its removal from a cell that has a critical role in this process. The dissociation can be suppressed by the topoisomerase-2 inhibitors novobiocin, ellipticine and etoposide. Breaks in the DNA also inhibit the process. The dissociation of the dye requires that DNA remain intact along a region of at least several thousand base pairs. It is proposed that DNA in mammalian cells is a dynamic, conformationally nonstable system and that topologically closed loops consisting of several thousand base pairs constantly appear and disappear in chromatin.
荧光染料Hoechst 33342紧密结合于DNA小沟，由于能量依赖过程，它可在体内从DNA中有效提取。在此过程中，关键作用的是染料从DNA上解离，而非从细胞中去除。拓扑异构酶-2抑制剂新生霉素、椭圆玫瑰树碱和依托泊苷可抑制这种解离。DNA断裂也会抑制该过程。染料的解离要求DNA在至少几千个碱基对的区域内保持完整。有人提出，哺乳动物细胞中的DNA是一个动态的、构象不稳定的系统，由几千个碱基对组成的拓扑封闭环在染色质中不断出现和消失。
