College of Food Science and Technology, Bohai University, Jinzhou 121013, China.
Instrumental Analysis Center, Shanghai Jiao Tong University, Shanghai 200240, China.
Int J Biol Macromol. 2021 Mar 31;174:207-215. doi: 10.1016/j.ijbiomac.2021.01.112. Epub 2021 Jan 19.
Phenoloxidase (PO) is a typical metal enzyme, which requires metal ions as prosthetic groups to enable the full exertion of its activity. To study how metal ions affected the activity and structure of PO enzymes, while providing reference materials for in-depth investigations, we examined the effects of different metal ions (Cu, Zn, Mg, Ca, and Ba) on their activities. Furthermore, Cu and Mg were selected for further investigation through UV spectra, intrinsic fluorescence spectroscopy, AFM, and FTIR. It was revealed that Cu had a more obvious effect on PO compared to Mg. The PO could be activated when the concentrations of Cu and Mg were lower than 10 and 10 mol/L, respectively, and maximum PO activities (182.14% and 141.02%) were observed at 10 mol/L concentrations of Cu and Mg. When the concentrations of Cu and Mg were higher than 10 and 10 mol/L, the activities PO were inhibited. The results of the UV-vis and fluorescence spectra revealed that Cu shaped the tertiary structure of PO, whereas the effect of Mg was slight. The AFM results demonstrated that high concentrations of Cu and Mg resulted in PO aggregation. FTIR analysis indicated that the total content of PO α-helices and β-sheets decreased with higher concentrations of Cu and Mg.
酚氧化酶（PO）是一种典型的金属酶，需要金属离子作为辅基才能充分发挥其活性。为了研究金属离子如何影响 PO 酶的活性和结构，同时为深入研究提供参考材料，我们考察了不同金属离子（Cu、Zn、Mg、Ca 和 Ba）对其活性的影响。此外，通过紫外可见光谱、内源荧光光谱、原子力显微镜和傅里叶变换红外光谱进一步研究了 Cu 和 Mg。结果表明，Cu 对 PO 的影响比 Mg 更明显。当 Cu 和 Mg 的浓度分别低于 10 和 10 mol/L 时，PO 可以被激活，在 Cu 和 Mg 的浓度为 10 mol/L 时观察到最大的 PO 活性（182.14%和 141.02%）。当 Cu 和 Mg 的浓度高于 10 和 10 mol/L 时，PO 的活性受到抑制。紫外可见和荧光光谱的结果表明，Cu 形成了 PO 的三级结构，而 Mg 的影响较小。原子力显微镜结果表明，高浓度的 Cu 和 Mg 导致 PO 聚集。傅里叶变换红外分析表明，随着 Cu 和 Mg 浓度的增加，PO 的α-螺旋和β-折叠总含量减少。
