光谱法研究6-糠氨基嘌呤与牛血清白蛋白的相互作用

Studies on the Interaction of Kinetin with Sodium Dodecyl Sulfonate by Spectro Photometry

利用荧光光谱法、紫外光谱法、荧光寿命和圆二色光谱法等方法研究了6-糠氨基嘌呤(KT)与牛血清白蛋白(BSA)之间相互作用机理.结果表明,KT可以显著猝灭BSA的内源荧光,其猝灭机制为静态猝灭,猝灭常数Ksv在288 K和303 K时分别为1.45×104和1.42×104L/mol,Stern-Volmer曲线是两段相交于cKT=8.0×10-5mol/L的回归曲线,说明KT与BSA之间存在两类结合位点.数据处理及热力学参数计算表明:低浓度KT-BSA(cKT<8.0×10-5mol/L)的结合主要是疏水作用,结合位点数约为1;较高浓度KT(cKT>8.0×10-5mol/L)主要以氢键、范德华力与BSA结合,结合位点数为3.7.紫外光谱和圆二色光谱实验结果表明,KT的存在使BSA二级结构发生了改变.

The interaction mechanism of Kinetin（KT） with BSA was studied by the methods of fluorescence,fluorescence lifetime,UV absorption and CD spectrometries.KT could strongly quench the intrinsic fluorescence of BSA by static quenching.The quenching constants of KT with BSA at two temperatures（288K and 303K） were obtained as 1.45×104 and 1.42×104 L/mol.The Stern Volmer curve had an intersection at cKT=8.0×10-5 mol/L,which indicated that KT bound to different binding sites on BSA.The analytical results of fluorescence data showed when cKT8.0×10-5 mol/L,the number of binding sites was near 1,and when cKT8.0×10-5 mol/L,the number of binding sites was approximately 3.7.The thermodynamic parameters were calculated by Van＇t Hoff equation.The enthalpy change enthalpy change（ΔH） and entropy change（ΔS） were calculated at two concentration of KT.The results suggested that the hydrophobic interaction might play a main role in the interaction of KT（cKT8.0×10-5 mol/L） with the BSA,while cKT8.0×10-5 mol/L the hydrogen bonding and Vander Waals forces became major.The investigations of the UV/Vis and CD spectra of the system showed that the secondary structure of BSA was changed in presence of KT.