Multispectroscopic and computational simulation insights into the inhibition mechanism of epigallocatechin-3-gallate on polyphenol oxidase
Multispectroscopic and computational simulation insights into the inhibition mechanism of epigallocatechin-3-gallate on polyphenol oxidase
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DOI：
10.1016/j.foodchem.2022.133415
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发表时间：
2022-06-08
期刊：
影响因子：
8.8
通讯作者：
Liao, Xiaojun
中科院分区：
文献类型：
--
作者：
Tian, Xuezhi;Rao, Lei;Liao, Xiaojun
多酚氧化酶（PPO）介导的酶促布朗宁广泛存在于水果、蔬菜和水产品中，每年造成巨大的经济损失。表没食子儿茶素没食子酸酯（epigallocatechin-3-gallate，EGCG）对多酚氧化酶（PPO）具有很强的亲和性和抑制作用。为了探索抑制机制，多光谱方法和计算机模拟。最初，EGCG以混合型方式可逆地抑制PPO活性。通过荧光发射光谱和圆二色性分析，研究了PPO与EGCG结合后的构象和二级结构变化。分子对接和动力学模拟结果表明，EGCG可以通过疏水堆积和氢键与PPO的双核铜结构域紧密结合。此外，EGCG可能作为一个接头，在另一个结合位点与不同的PPO分子相互作用。透射电镜观察表明，EGCG诱导了PPO的聚集。因此，EGCG对PPO的抑制机制包括竞争催化中心和诱导聚集。
Polyphenol oxidase (PPO)-mediated enzymatic browning occurs in fruit, vegetables and aquatic products and causes huge economic losses every year. In this study, epigallocatechin-3-gallate (EGCG) displayed high affinity for and efficient inhibitory capacity against PPO. To explore the inhibition mechanism, multispectroscopic methods and computational simulations were implemented. Initially, EGCG inhibited PPO activity reversibly in a mixed-type manner. Then, the conformation and secondary structure changes of PPO after binding with EGCG were discovered by fluorescence emission spectra and circular dichroism. Molecular docking and dynamic simulation results revealed that EGCG could tightly bind with the binuclear copper domain of PPO through hydrophobic stacking and hydrogen bonds. Moreover, EGCG might act as a linker to interact with different PPO molecules at another binding site. Transmission electron microscopy observation suggested that EGCG induced the aggregation of PPO. Therefore, the inhibition mechanism of EGCG on PPO included competition for catalytic centers and induced aggregation.