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Abstract：
The conversion of Kraft lignin in plant biomass into renewable chemicals, aiming at harvesting aromatic compounds, is a challenge process in biorefinery. Comparing to the traditional chemical methods, enzymatic catalysis provides a gentle way for the degradation of lignin. Alternative to natural enzymes, artificial enzymes have been received much attention for potential applications. We herein achieved the biodegradation of Kraft lignin using an artificial peroxidase rationally designed in myoglobin (Mb), F43Y/T67R Mb, with a covalently linked heme cofactor. The artificial enzyme of F43Y/T67R Mb has improved catalytic efficiencies at mild acidic pH for phenolic and aromatic amine substrates, including Kraft lignin and the model lignin dimer guaiacylglycerol-β-guaiacyl ether (GGE). We proposed a possible catalytic mechanism for the biotransformation of lignin catalyzed by the enzyme, based on the results of kinetic UV-Vis studies and UPLC-ESI-MS analysis, as well as molecular modeling studies. With the advantages of F43Y/T67R Mb, such as the high-yield by overexpression in E. coli cells and the enhanced protein stability, this study suggests that the artificial enzyme has potential applications in the biodegradation of lignin to provide sustainable bioresource.
摘要：
将植物生物质中的硫酸盐木质素转化为可再生化学物质，旨在收获芳香族化合物，是生物炼制中的一个挑战过程。与传统的化学方法相比,酶催化为木质素的降解提供了一种温和的途径。替代天然酶，人工酶因其潜在的应用而备受关注。我们在此使用在肌红蛋白（Mb）中合理设计的人工过氧化物酶实现了硫酸盐木质素的生物降解，F43Y/T67RMb,与共价连接的血红素辅因子。F43Y/T67RMb的人工酶在温和酸性pH下对酚胺和芳香胺底物具有提高的催化效率，包括硫酸盐木质素和模型木质素二聚体愈创酰甘油-β-愈创酰醚(GGE)。我们提出了酶催化木质素生物转化的可能催化机理，基于动力学UV-Vis研究和UPLC-ESI-MS分析的结果，以及分子建模研究。凭借F43Y/T67RMb的优势，如在大肠杆菌细胞中过表达的高产率和增强的蛋白质稳定性，这项研究表明，人工酶在木质素的生物降解中具有潜在的应用，可以提供可持续的生物资源。
