基于光谱学结合分子模拟研究咖啡酸和对香豆酸与脲酶的相互作用

Studying the interaction of caffeic acid and p-coumaric acid with urease based on spectroscopy combined with molecular simulation

目的探究咖啡酸(caffeic acid,CA)和对香豆酸(p-coumaric acid,PCA)与脲酶的相互作用。方法以具有细微分子结构差异的CA和PCA为研究对象,通过荧光光谱获取其对脲酶的荧光淬灭常数及结合常数,使用圆二色谱结合变温技术考察不同温度条件下CA和PCA对脲酶二级结构的影响,利用分子模拟方法探讨CA和PCA与脲酶的结合位点与空间构象。结果CA和PCA对脲酶均属于静态淬灭,与脲酶的结合是自发形成的(ΔG°<0),且结合摩尔比为1:1。CA对脲酶二级结构的影响高于PCA,且在温度为300.15 K时CA与脲酶的亲和力远高于PCA,而它们与脲酶的结合稳定性随温度的升高而降低。分子对接进一步证明了CA与脲酶的结合能力强于PCA,并且在结合过程中氢键为主要相互作用力,CA和PCA与脲酶结合在双镍活性位点周边。结论CA和PCA可以与脲酶自发结合,其稳定性随着温度的升高而下降,研究结果为基于构效关系的天然小分子的功能性应用提供新思路。

Objective To investigate the interaction between caffeic acid(CA)and p-coumaric acid(PCA)and urease.Methods The quenching constants and binding constants of CA and PCA with subtle molecular structure differences on urease were obtained by fluorescence spectra.The effects of CA and PCA on the secondary structure of urease at different temperatures were investigated by circular dichroism combined with temperature change technology.The binding sites and spatial conformations of CA and PCA with urease were studied by molecular simulation method.Results The fluorescence quenching types of urease by CA and PCA were static quenching,and the binding to urease was spontaneous(ΔG°0),and the molar ratio of binding was 1:1.The effect of CA on the secondary structure of urease was higher than that of PCA,and the affinity of CA to urease was much higher than that of PCA at 300.15 K,while the binding stability of CA to urease decreased with the increase of temperature.Molecular docking further proved that the binding ability of CA and urease was stronger than that of PCA,and the hydrogen bond was the main interaction force during the binding process,and CA and PCA bound to urease around the active site of double nickel.Conclusion CA and PCA can spontaneously bind to urease,and their stability decreases with increasing temperature.The research findings provide new insights into the functional applications of natural small molecules based on structure-activity relationships.