荷叶中紫云英苷和牛血清白蛋白相互作用的光谱学研究

Spectroscopic Investigation on the Interaction between Astragalin in Lotus Leaf and Bovine Serum Albumin

本文采用荧光光谱法、紫外光谱法研究在生理条件(pH=7.4)下荷叶中紫云英苷(AST)与牛血清白蛋白(BSA)的相互作用。结果表明AST可与BSA结合并通过静态猝灭作用机制对BSA内源性荧光进行猝灭。在温度为298K及308K时,测得其猝灭速率常数(Kq)分别为4.31×1013L/mol/s和3.72×1013L/mol/s;结合常数(Kd)分别为2.009×105L/mol和0.927×105L/mol;结合位点数(n)分别为0.943和0.893。依据298K时测定的反应自由能变(△G0=-30.25kJ/mol),反应焓变(△H0=-59.02kJ/mol)及反应熵变(△S0=-96.54J/mol/K),结果发现AST与BSA间的结合反应可自发进行且其作用力主要表现为氢键和范德华力。此外,根据Frster非辐射能量转移理论得到AST与BSA之间的结合距离(r)为4.13nm,表明非辐射能量可从BSA转移至AST。

The interaction between astragalin（AST）in lotus leaf and bovine serum albumin（BSA）in physiological condition（pH=7.4）was studied by fluorescence spectroscopy and ultraviolet absorption spectroscopy.The results demonstrated that AST could bind to BSA and quenched the intrinsic fluorescence of BSA through static quenching mechanism.The quenching rate constants of biomoleculer,the binding constants,and the number of binding sites between AST and BSA were Kq=4.31×1013 L/mol/s and 3.72×1013 L/mol/s,Kd=2.009×105 L/mol and 0.927×105 L/mol,n=0.943 and 0.893 at 298 K and 308 K,respectively.According to the free energy change（△G0=-30.25 kJ/mol）,the enthalpy change（△H0=-59.02 kJ/mol）and the entropy change（△S0=-96.54 J/mol/K）obtained at 298 K,the binding of BSA to AST was found to be spontaneous and the interaction between BSA and AST was driven mainly by hydrogen bonds and van der Waals forces.In addition,based on the Frster theory of non-radiation energy transfer,the binding distance（r=4.13 nm）between AST and BSA was close enough to transfer non-radiation energy from BSA to AST.