Xiong Zhiqiang, Liu Wei, Zhou Lei, Zou Liqiang, Chen Jun
State Key Laboratory of Food Science and Technology, Nanchang University, No. 235 Nanjing East Road, Nanchang, Jiangxi 330047, China.
State Key Laboratory of Food Science and Technology, Nanchang University, No. 235 Nanjing East Road, Nanchang, Jiangxi 330047, China.
Food Chem. 2016 Jul 15;203:430-439. doi: 10.1016/j.foodchem.2016.02.045. Epub 2016 Feb 6.
It has been revealed that some polyphenols can prevent enzymatic browning caused by polyphenoloxidase (PPO). Apigenin, widely distributed in many fruits and vegetables, is an important bioactive flavonoid compound. In this study, apigenin exhibited a strong inhibitory activity against PPO, and some reagents had synergistic effect with apigenin on inhibiting PPO. Apigenin inhibited PPO activity reversibly in a mixed-type manner. The fact that inactivation rate constant (k) of PPO increased while activation energy (Ea) and thermodynamic parameters (ΔG, ΔH and ΔS) decreased indicated that the thermosensitivity and stability of PPO decreased. The conformational changes of PPO were revealed by fluorescence emission spectra and circular dichroism. Atomic force microscopy observation suggested that the dimension of PPO molecules was larger after interacting with apigenin. Moreover, computational docking simulation indicated that apigenin bound to PPO and inserted into the hydrophobic cavity of PPO to interact with some amino acid residues.
据揭示，一些多酚可以防止多酚氧化酶（PPO）引起的酶促褐变。芹菜素广泛分布于许多水果和蔬菜中，是一种重要的生物活性黄酮类化合物。在本研究中，芹菜素对PPO表现出较强的抑制活性，并且一些试剂与芹菜素在抑制PPO方面具有协同作用。芹菜素以混合型方式可逆地抑制PPO活性。PPO的失活速率常数（k）增加而活化能（Ea）和热力学参数（ΔG、ΔH和ΔS）降低，这一事实表明PPO的热敏感性和稳定性降低。通过荧光发射光谱和圆二色性揭示了PPO的构象变化。原子力显微镜观察表明，与芹菜素相互作用后PPO分子的尺寸更大。此外，计算对接模拟表明芹菜素与PPO结合并插入PPO的疏水腔中与一些氨基酸残基相互作用。
