Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Oeiras, Portugal.
Bioresour Technol. 2012 Nov;124:371-8. doi: 10.1016/j.biortech.2012.08.023. Epub 2012 Aug 11.
The aim of the present work is to provide insight into the mechanism of laccase reactions using syringyl-type mediators. We studied the pH dependence and the kinetics of oxidation of syringyl-type phenolics using the low CotA and the high redox potential TvL laccases. Additionally, the efficiency of these compounds as redox mediators for the oxidation of non-phenolic lignin units was tested at different pH values and increasing mediator/non-phenolic ratios. Finally, the intermediates and products of reactions were identified by LC-MS and (1)H NMR. These approaches allow concluding on the (1) mechanism involved in the oxidation of phenolics by bacterial laccases, (2) importance of the chemical nature and properties of phenolic mediators, (3) apparent independence of the enzyme's properties on the yields of non-phenolics conversion, (4) competitive routes involved in the catalytic cycle of the laccase-mediator system with several new C-O coupling type structures being proposed.
本工作旨在深入了解使用愈创木型介体的漆酶反应机制。我们使用低 CotA 和高氧化还原电势 TvL 漆酶研究了愈创木型酚类的 pH 依赖性和氧化动力学。此外，还在不同 pH 值和增加的介体/非酚类比例下测试了这些化合物作为氧化非酚类木质素单元的氧化还原介体的效率。最后，通过 LC-MS 和 (1)H NMR 鉴定了反应的中间体和产物。这些方法可以得出以下结论：(1) 细菌漆酶氧化酚类的(1) 机制；(2) 酚类介体的化学性质和特性的重要性；(3) 酶的性质对非酚类转化率的产率的明显独立性；(4) 漆酶-介体系统催化循环中涉及的竞争途径，并提出了几种新的 C-O 偶联类型结构。
