论文部分内容阅读
以亚甲基蓝(MB)为分子探针,用紫外-可见光谱、荧光光谱、荧光偏振和圆二色光谱研究了百草枯与小牛胸腺(ctDNA)的相互作用.MB分子主要以嵌插方式结合到ctDNA双螺旋结构上,而百草枯则以非竞争方式抑制MB与ctDNA的结合;百草枯对MB-ctDNA体系的荧光偏振以及百草枯对ctDNA圆二色光谱的影响,结果均表明百草枯与ctDNA主要作用方式为非嵌插结合.NaCl对百草枯与ctDNA的结合具有显著的抑制作用,因此可以推断带正电荷的百草枯离子可能通过与ctDNA链上带负电荷的磷酸基以静电相吸的方式结合而堆积在ctDNA双螺旋表面,引起ctDNA收缩,减弱了结合位点附近MB与ctDNA的静电作用;这可能由于钠离子中和了ctDNA磷酸基上的负电荷,从而削弱了百草枯与ctDNA间的静电作用.通过Scatchard方程计算,获得了百草枯与ctDNA的结合常数为1.80×104L·mol-1.
The interaction between paraquat and calf thymus (ctDNA) was investigated by UV-Vis, fluorescence, fluorescence polarization and circular dichroism using methylene blue (MB) as a molecular probe. ctDNA double helix structure, and paraquat non-competitive inhibition of MB and ctDNA binding; Paraquat on MB-ctDNA fluorescence polarization and paraquat ctDNA circular dichroism spectrum results show that paraquat and ctDNA The main mode of action is non-intercalating combination.NaCl has a significant inhibitory effect on the combination of paraquat and ctDNA, therefore, it can be inferred that the positively charged paraquat ions may be electrostatically attracted by negatively charged phosphate groups on the ctDNA chain Way binding and accumulation in the ctDNA double helix surface, causing ctDNA contraction, weakening the binding sites near the MB and ctDNA electrostatic interaction; This may be due to the neutralization of sodium ions ctDNA phosphate negative charge, thus weakening the paraquat and ctDNA The electrostatic interaction between paraquat and ctDNA was obtained through the Scatchard equation. The binding constant was 1.80 × 104 L · mol-1.