西那沙星与牛血清白蛋白的相互作用及共存金属离子影响的研究

Studies on Interaction of Sinafloxacin with Bovine Serum Albumin and Effect of the Coexistent Metal Ions on the Reaction

应用荧光光谱法、紫外分光光度法研究了在不同酸度、温度条件下,西那沙星(Sinafloxacin)与牛血清白蛋白(bovine serum albumins,BSA)的相互作用,研究表明:西那沙星对BSA内源荧光的猝灭机制属于形成复合物所引起的静态猝灭,利用荧光猝灭双倒数图计算了西那沙星与牛血清白蛋白之间的结合常数KD,根据F rster非辐射能量转移理论计算出西那沙星与牛血清白蛋白结合时授体-受体间的结合距离r=3.64 nm、能量转移效率E=0.163,表明两者之间有较强的作用,并根据热力学参数确定了西那沙星与牛血清白蛋白之间的主要作用力类型为静电作用力,同时采用同步荧光、三维荧光技术考察了西那沙星对BSA构象的影响。此外,讨论了共存Cu2+,Fe3+,Zn2+,Mg2+对西那沙星与BSA结合作用的影响。为探讨西那沙星在生物体内与蛋白质的作用机理和生物学效应提供了理论依据。

Serum albumin is the most abundant protein in plasma.It can bind with many intrinsic and extrinsic materials.The study of the interaction between serum albumin and drugs is a very important task in life science and chemistry.Quinolone drug is a kind of antibacterial drugs which have been used widely in clinical medicine,but its pharmacology and toxicology still have to be studied further.Sinafloxacin is a new quinolone antibiotics.The interaction between sinafloxacin and bovine serum albumin（BSA） at different temperatures and pH was investigated by fluorescence and UV absorption spectroscopy.The experimental results demonstrate that the fluorescence quenching of BSA by sinafloxacin is a result of the formation of sinafloxacin-BSA complex and the quenching mechanism is mainly static quenching.The interaction association constants of BSA and sinafloxacin were determined from the double reciprocal Lineweaver-Burk plot.The binding distance（r=3.64 nm）and energy transfer efficiency（E=0.163） between donor（BSA）and acceptor（sinafloxacin） were obtained based on Frster＇s non-radiative energy transfer theory.There is a strong interaction between sinafloxacin and BSA.From thermodynamic coordination it can be judged that the binding force between sinafloxacin and BSA is mainly electro-static force.The effect of sinafloxacin on the conformation of BSA was analyzed by synchronous fluorescence spectrometry and three-dimensional fluorescence spectrometry.The emission maximum of tyrosine residues does not show a significant shift,while the small blue shift of tryptophan residues indicates that the hydrophobicity of microenvironment was increased.In addition,in the plasma,there are some metal ions,which can participate in many important vital actions and affect the reactions of the drugs with the serum albumins.So the effect of Cu（Ⅱ）,Fe（Ⅲ）, Zn（Ⅱ） and Mg（Ⅱ） on the binding constant of sinafloxacin to BSA was also discussed and it was shown that the interaction between BSA and sinafloxacin was decreased.In short,the results offer a reference for the studies on the biological effects and action mechanism of sinafloxacin with albumins in vivo.