State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, China.
Division of Accounting, Nanchang University, Nanchang 330047, China.
Food Funct. 2020 Jun 24;11(6):4892-4902. doi: 10.1039/d0fo00003e.
The inhibition mechanism of epicatechin gallate (ECG) on tyrosinase was investigated by multispectroscopic techniques combined with molecular docking and molecular dynamics simulation. The results demonstrated that ECG suppressed the activity of tyrosinase in a reversible mixed-inhibition with a half inhibitory concentration (IC50) of (1.13 ± 0.82) × 10-5 mol L-1. Binding of ECG to tyrosinase led to the formation of a complex with the binding constant (Ksv) of 4.03 × 104 L mol-1 at 298 K which was stabilized by hydrophobic forces. The complex formation induced the intrinsic fluorescence quenching and secondary structure change of tyrosinase. Molecular docking results showed that hydrophobic and hydrogen bonding forces played a dominant role in the binding of ECG to tyrosinase, affecting the binding affinity of l-dopa to tyrosinase, leading to a decrease in tyrosinase activity. Molecular dynamics analysis indicated that ECG led to the stretching of the basic framework structure of tyrosinase and slightly influenced the microenvironment of amino acid residues. The research might provide new perspectives on the inhibition mechanism of epicatechin gallate on tyrosinase and a theoretical basis for the prevention and treatment of pigmented skin diseases and anti-browning of catechin as a food supplement.
表儿茶素没食子酸酯（ECG）对酪氨酸酶抑制作用的研究采用多种光谱技术结合分子对接和分子动力学模拟。结果表明，ECG 以可逆的混合抑制方式抑制酪氨酸酶的活性，其半抑制浓度（IC50）为（1.13±0.82）×10-5mol/L。ECG 与酪氨酸酶结合形成复合物，298 K 时结合常数（Ksv）为 4.03×104L/mol，该复合物通过疏水作用力稳定。复合物的形成诱导了酪氨酸酶的内源荧光猝灭和二级结构变化。分子对接结果表明，疏水作用力和氢键在 ECG 与酪氨酸酶的结合中起主导作用，影响 l-多巴与酪氨酸酶的结合亲和力，导致酪氨酸酶活性降低。分子动力学分析表明，ECG 导致酪氨酸酶基本框架结构的拉伸，略微影响氨基酸残基的微环境。该研究可能为表儿茶素没食子酸酯对酪氨酸酶的抑制机制提供新的视角，并为预防和治疗色素性皮肤病以及儿茶素作为食品添加剂的抗褐变提供理论依据。
