多光谱结合分子对接分析表儿茶素与酸性磷酸酶的相互作用

Analysis of the Interaction between Epicatechin and Acid Phosphatase by Multi-spectroscopies and Molecular Docking

酸性磷酸酶是风味物质(肌苷酸)降解的一种关键酶,抑制该酶对保持贮藏过程中水产品的风味非常重要。采用紫外-可见吸收光谱、荧光光谱、圆二色光谱和分子对接等方法研究表儿茶素与酸性磷酸酶的相互作用,结果表明:表儿茶素能有效抑制酸性磷酸酶的活性,IC_(50)值为0.184 mmol/L,其抑制类型为混合型抑制。当表儿茶素浓度为0.1 mmol/L时,抑制常数(Ki)为1.025 mmol/L。表儿茶素可使酸性磷酸酶发生动态荧光猝灭。在298 K下,酸性磷酸酶的结合常数(Ka)为1.455×10^(5)L/mol,酸性磷酸酶与表儿茶素之间的主要相互作用力是氢键和范德华力。表儿茶素使酸性磷酸酶的二级结构发生改变,使其α-螺旋增加,而β折叠、β-转角和无规则卷曲减少。研究结果为贮藏过程中抑制水产品中肌苷酸的降解提供了新思路。

Acid phosphatase(ACP)is a key enzyme involved in the degradation of flavorful substances inosinic acid(IMP).Therefore,inhibition of ACP is very important to maintain the flavor of aquatic products during storage.This study investigated the interaction and inhibitory mechanisms of epicatechin(EC)on ACP by UV-Vis absorption spectroscopy,fluorescence spectroscopy,circular dichroism and molecular docking.The results showed that EC could effectively inhibit ACP activity,and the IC_(50)value was 0.184 mmol/L.It was reversible inhibitor of ACP,and the inhibition mechanism was the un-competitive type by kinetic analysis.The inhibition constant(Ki)was 1.025 mmol/L when the concentration of EC was 0.1 mmol/L.The fluorescence of ACP was quenched by the interaction with EC and the quenching mode was dynamic quenching.The binding constant(Ka)of ACP was 1.455×10^(5) L/mol after adding EC at 298 K.The interaction of ACP with EC was driven by hydrogen bonds and van der Waals forces.EC altered the secondary structure of ACP,resulting in an increase in α-helix and a decrease in β-folding,β-turning and random coil.This study provides a new idea to inhibit the degradation of IMP in aquatic products during storage.