八羟基喹啉铜(Ⅱ)配合物的DNA结合和切割活性及与牛血清白蛋白相互作用（英文）

DNA binding,DNA cleavage and BSA interaction of a bis-8-hydroxyquinoline copper(Ⅱ) complex

利用紫外吸收光谱、荧光光谱、圆二色光谱(CD)和琼脂糖凝胶电泳等手段研究了八羟基喹啉铜(Ⅱ)配合物Cu[8-OHQ]2与DNA和蛋白质的相互作用.实验结果表明,在生理条件下,Cu[8-OHQ]2能通过插入方式较强的与CT-DNA结合,诱导DNA构象的改变.其本征结合常数Kb为1.15(±0.01)×105 L/mol,表观结合常数Kapp为4.21×106 L/mol.再者,琼脂糖凝胶电泳实验表明,在生理条件和抗坏血酸(Vc)存在情况下,Cu[8-OHQ]2能有效地将超螺旋pBR322质粒DNA切割成缺刻和线性,甚至降解为小的片断.机理研究表明扩散的·OH,H2O2和1 O2都不是在切割过程中起作用的活性氧物种(ROS);copper-oxo中间体可能是此切割过程中主要的活性氧物种.另外,Cu[8-OHQ]2也能以适中的结合力与牛血清白蛋白(BSA)结合而猝灭BSA内源荧光,猝灭机理为静态猝灭.所有这些结果表明Cu[8-OHQ]2具有作为潜在化疗试剂的生物活性.

The interactions between DNA/protein and the bis-8-hydroxyquinoline copper（II）complex,Cu[8-OHQ]2,were investigated under physiological conditions using UV-vis absorption,fluorescence,circular dichroism（CD）,and agarose gel electrophoresis.The experimental results suggest Cu[8-OHQ]2could strongly bind to calf thymus DNA（CT-DNA）through an intercalative mode and induce a remarkable conformational variation of DNA.The intrinsic binding constant Kbof Cu[8-OHQ]2to DNA is 1.15（±0.01）×105 L/mol and the apparent binding constant Kappis 4.21×106 L/mol.Furthermore,agarose gel electrophoresis revealed,in the presence of ascorbic acid（Vc）under nearly physiological conditions,Cu[8-OHQ]2could efficiently cleave the supercoiled pBR322 plasmid DNA into its nicked and linear forms,even degrade into undetectable minor fragments.Mechanism studies demonstrated diffusible·OH,H2O2 and 1 O2 are not the effective reactive oxygen species（ROS）in the cleavage process mediated by the complex and the copper-oxo species might be responsible for the cleavage.Additionally,Cu[8-OHQ]2could also bind to bovine serum albumin（BSA）with a medium affinity and quench the intrinsic fluorescence of BSA through a single static quenching mechanism.All these results suggest that Cu[8-OHQ]2exhibits biological action as a potential chemotherapy agent.