亚甲蓝类似物的合成及其与牛血清白蛋白相互作用的研究

摘要

目的 合成3种亚甲蓝类似物3,7-二(二正丙胺基)-吩噻嗪-5-鎓碘化物、3,7-二(二正丁胺基)-吩噻嗪-5-鎓碘化物和3,7-二(二正戊胺基)-吩噻嗪-5-鎓碘化物,并研究模拟生理条件下这3种亚甲蓝类似物与牛血清白蛋白的相互作用.方法 通过1H-NMR及MS对这3种亚甲蓝类似物进行结构表征,应用荧光光谱法研究了模拟生理条件下这3种亚甲蓝类似物与牛血清白蛋白的相互作用.结果 3种亚甲蓝类似物和BSA相互作用形成了蛋白质-药物复合物并猝灭其固有荧光,亚甲蓝类似物与BSA相互作用过程的ΔG0<0,亚甲蓝类似物与BSA荧光残基间的距离r均小于7 nm.结论 亚甲蓝类似物和BSA相互作用的猝灭机制为静态猝灭,二者之间的反应是自发进行的.非辐射能量转移理论表明BSA与亚甲蓝类似物之间存在非辐射能量转移.同步荧光光谱和三维荧光光谱的研究结果表明,亚甲蓝类似物与BSA的相互作用导致BSA构象发生变化.%Objective To synthesize a series of methylene blue derivants,N3,N3,N7,N7-Tetra-n-propyl-3,7-diaminophenothiazin-5-ium iodide,N3,N3,N7,N7-Tetra-n-butyl-3,7-diaminophenothiazin-5-ium iodide and N3,N3,N7,N7-Tetra-n-pentyl-3,7-diaminophenothiazin-5-ium iodide,and study the interactions between these methylene blue derivants and bovine serum albumin(BSA) under physiological condition.Methods These compounds were characterized by means of MS and 1H-NMR,and the interactions between these methylene blue derivants and bovine serum albumin(BSA) under physiological condition were studied using fluorescence spectroscopy.Results The fluorescence of BSA was quenched remarkably by these methylene blue derivants due to the formation of complexes,Gibbs free energy change(ΔG0) was negative.The binding distance between the tryptophan residue of BSA and these methylene blue derivants was less than 7 nm.Conclusion The fluorescence quenching mechanisms of BSA by these methylene blue derivants were considered as static quenching,the binding process was a spontaneous process and the energy transfer from the tryptophan residue of BSA to these methylene blue derivants can occur according to the Frster non-radioactive resonance energy transfer theory.In addition,the results of synchronous fluorescence spectra and three-dimensional fluorescence spectra showed that interaction between the methylene blue derivants and BSA can induce conformational changes in BSA.