光谱和分子模拟法研究乙硫异烟胺与木瓜蛋白酶的分子作用机制

利用荧光光谱、紫外光谱和分子模拟方法研究了乙硫异烟胺(TH1314)与木瓜蛋白酶之间的相互作用, 求得了不同温度下的结合常数K. 研究结果表明, 静态猝灭是导致乙硫异烟胺对木瓜蛋白酶荧光猝灭的主要原因. 通过计算热力学参数, 可知乙硫异烟胺与木瓜蛋白酶相互作用的吉布斯自由能表现为较大的负值, 并结合作用过程的焓变和熵变推断出乙硫异烟胺与木瓜蛋白酶之间的作用力是以疏水和氢键作用为主. 同时, 利用紫外光谱和同步荧光光谱定性讨论了乙硫异烟胺对木瓜蛋白酶构象的影响. 分子模拟研究表明, 乙硫异烟胺与木瓜蛋白酶的相互作用不仅存在疏水作用, 而且有氢键作用, 这与光谱及热力学研究结果是一致的.

Mechanism of Molecular Interaction between Ethionamide and Papain:Spectroscopic and Molecular Simulation Investigations

The interaction between ethionamide and papain was investigated by fluorescence spectroscopy, UV-Vis absorption spectroscopy and molecular simulation, and the binding constants K were obtained at different temperatures. The experimental results suggested that static quenching was the main reason for the fluorescence quenching process. Thermodynamic data showed that the change for Gibbs free energy of the binding was a large negative value, which indicated that the interaction between ethionamide and papain was driven mainly by hydrophobic force and hydrogen bond. Additionally, the effects of ethionamide on papain conformation were investigated by synchronous spectroscopy and UV-Vis absorption spectroscopy. The study of molecular simulation indicated that there was not only hydrophobic interaction on the binding of ethionamide to papain, but there was also hydrogen bond interaction, which was consistent with the results of spectra and thermodynamics.