Key Laboratory for Molecular Enzymology and Engineering of Ministry of Education, School of Life Sciences, Jilin University, Changchun 130012, China.
School of Life Sciences, Jilin University, Changchun 130012, China.
Int J Mol Sci. 2024 Sep 19;25(18):10074. doi: 10.3390/ijms251810074.
Polyphenol oxidase (PPO) plays a key role in the enzymatic browning process, and this study employed Gaussian-accelerated molecular dynamics (GaMD) simulations to investigate the catalytic efficiency mechanisms of lotus root PPO with different substrates, including catechin, epicatechin, and chlorogenic acid, as well as the inhibitor oxalic acid. Key findings reveal significant conformational changes in PPO that correlate with its enzymatic activity. Upon substrate binding, the alpha-helix in the Q53-D63 region near the copper ion extends, likely stabilizing the active site and enhancing catalysis. In contrast, this helix is disrupted in the presence of the inhibitor, resulting in a decrease in enzymatic efficiency. Additionally, the F350-V378 region, which covers the substrate-binding site, forms an alpha-helix upon substrate binding, further stabilizing the substrate and promoting catalytic function. However, this alpha-helix does not form when the inhibitor is bound, destabilizing the binding site and contributing to inhibition. These findings offer new insights into the substrate-specific and inhibitor-induced structural dynamics of lotus root PPO, providing valuable information for enhancing food processing and preservation techniques.
多酚氧化酶（PPO）在酶促褐变过程中起着关键作用，本研究采用高斯加速分子动力学（GaMD）模拟方法，研究了具有不同底物（包括儿茶素、表儿茶素和绿原酸）以及抑制剂草酸的莲藕 PPO 的催化效率机制。研究结果表明，PPO 的构象发生了显著变化，这与它的酶活性相关。在底物结合后，靠近铜离子的 Q53-D63 区域的α-螺旋延伸，可能稳定了活性部位并增强了催化作用。相比之下，在抑制剂存在的情况下，该螺旋被破坏，导致酶的效率降低。此外，覆盖底物结合部位的 F350-V378 区域在底物结合后形成α-螺旋，进一步稳定了底物并促进了催化功能。然而，当抑制剂结合时，该α-螺旋不会形成，破坏了结合部位并导致抑制作用。这些发现为莲藕 PPO 的底物特异性和抑制剂诱导的结构动力学提供了新的见解，为提高食品加工和保存技术提供了有价值的信息。
