中文摘要：

在花蕾(BLM ) helicase 的生物性质上学习 fleroxacin (FLRX ) 的效果的目的在 vitro 和在二个分子之间的相互作用的分子的机制的催化核心(BLM642-1290 helicase ) 。BLM642-1290 helicase 的方法 DNA 有约束力、摊开的活动在 helicase 受到 FLRX 的不同集中的条件下面是由荧光极化和胶化延迟试金的 assayed。在 helicase ATPase 活动的 FLRX 的效果被没有磷的试金基于 ATP 生产水解作用的无机的磷酸盐的一个比色的评价分析。在二个分子之间的相互作用的分子的机制是 assayed 由紫外并且荧光系列。结果而 DNA 有约束力的活动在 vitro 被支持，放松的 DNA 和 BLM642-1290 helicase 的 ATPase 活动被禁止。BLM-FLRX 建筑群通过一个有约束力的地点被形成，静电、恐水病的相互作用力量。而且， helicase 的内在的荧光被 FLRX 由于非放射性的精力转移熄灭。helicase 的生物活动被 FLRX 影响，它可能通过 allosteric 机制和处于低 helicase 活动状态的酶符合构造的稳定，联合 ATP 水解作用到在 DNA 上摊开，并且堵住 helicase translocation 的混乱搁浅。结论 FLRX 可以影响 BLM642-1290 helicase 的生物活动和符合构造，并且 DNA helicase 可以为一些疾病被用作一个有希望的药目标。

英文摘要：

Objective To study the effect of fleroxacin （FLRX） on biological properties of Bloom （BLM） helicase catalytic core （BLM 642-2290 helicase） in vitro and the molecular mechanism of interaction between the two molecules. Methods DNA-binding and unwinding activities of BLM 642-1290 helicase were assayed by fluorescence polarization and gel retardation assay under conditions that the helicase was subjected to different concentrations of FLRX. Effect of FLRX on helicase ATPase activity was analyzed by phosphorus-free assay based on a colorimetric estimation of ATP hydrolysis-produced inorganic phosphate. Molecular mechanism of interaction between the two molecules was assayed by ultraviolet and fluorescence spectra. Results The DNA unwinding and ATPase activities of BLM 642-1290 helicase were inhibited whereas the DNA-binding activity was promoted in vitro. A BLM-FLRX complex was formed through one binding site, electrostatic and hydrophobic interaction force. Moreover, the intrinsic fluorescence of the helicase was quenched by FLRX as a result of non-radioactive energy transfer. The biological activity of helicase was affected by FLRX, which may be through an allosteric mechanism and stabilization of enzyme conformation in low helicase activity state, disruption of the coupling of ATP hydrolysis to unwinding, and blocking helicase translocation on DNA strands. Conclusion FLRX may affect the biological activities and conformation of BLM 642-1290 helicase, and DNA helicase may be used as a promising drug target for some diseases.