荧光法研究橙皮苷、淫羊藿苷与溶菌酶的相互作用

Study on the Interaction of Hesperidin or Icariin with Lysozyme by Fluorescence Spectroscopy

应用荧光光谱法研究了生理pH条件下橙皮苷或淫羊藿苷与溶菌酶的相互作用。研究发现,橙皮苷或淫羊藿苷对溶菌酶内源性荧光产生强烈的猝灭作用,测定了不同温度下橙皮苷或淫羊藿苷与溶菌酶反应的猝灭常数,并得出橙皮苷对溶菌酶的荧光猝灭过程为动态猝灭,淫羊藿苷对溶菌酶的荧光产生静态和动态并存的复合猝灭方式。由van’t Hoff方程式计算出橙皮苷或淫羊藿苷与溶菌酶反应的热力学参数:焓变ΔH和熵变ΔS值分别为20.29 kJ.mol-1,146.28 J.mol-1.K-1和-3.47 kJ.mol-1和81.16 J.mol-1.K-1,表明了橙皮苷与溶菌酶的作用力是以疏水作用为主,而淫羊藿苷与溶菌酶的作用力主要是静电引力,生成自由能变ΔG均为负值,表明橙皮苷或淫羊藿苷与溶菌酶的作用过程是一个熵增加、Gibbs自由能降低的自发过程。根据F ster非辐射能量转移理论求出了橙皮苷、淫羊藿苷与溶菌酶色氨酸残基之间的结合距离分别为1.34和1.24 nm。同步荧光研究表明橙皮苷、淫羊藿苷能够使溶菌酶的构象发生变化。

The interaction of hesperidin（HES） or icariin（ICA） and lysozyme（LYS） was studied by fluorescence spectroscopy in physiological buffer solution.It was observed that there was a strong fluorescence quenching effect of hesperidin or icariin on lysozyme.The quenching constants of the drugs with lysozyme were measured at different temperatures,and the quenching mechanism was suggested as dynamic quenching for HES-LYS system and both static and dynamic quenching for ICA-LYS system.The thermodynamic parameters of the interaction of hesperidin or icariin and lysozyme were measured according to the Van＇s Hoff equation： the enthalpy change（ΔH） and the entropy change（ΔS） of HES-LYS system and ICA-LYS system were calculated to be 20.29 kJ·mol^-1 and 146.28 J·mol^-1·K^-1,and-3.47 kJ·mol^-1 and 81.16 J·mol^-1·K^-1,respectively,which indicated that the interaction of hesperidin and lysozyme was driven mainly by hydrophobic force,whereas the interaction of icariin and lysozyme was driven mainly by electrostatic force. It was showed that the reaction processes of the two systems occurred spontaneously since Gibbs free energy change（ΔG） values were negative.The binding distances of hesperidin and icariin from the lysozyme tryptophan residue were calculated to be 1.34 nm and 1.24 nm,respectively,based on the Forster＇s theory of non-radiation energy transfer.The results of synchronous fluorescence spectra showed that the binding of hesperidin or icariin to lysozyme induced conformational changes in lysozyme.