Lignin Degradation by Phanerochaete chrysophorium: Biochemical Characterization of Extracellular Peroxidases

该项目的目的是加深我们对降解木质素的担子菌黄孢原毛平革菌的锰过氧化物酶(MnP)和木质素过氧化物酶(LIP)的了解。拟议项目的基本目标是进一步确定这些酶的结构、机制和功能，并阐明它们在木质素降解中的作用。用动力学方法、光学和核磁共振光谱研究MNP氧化锰的结合、化学计量和机理。此外，还将利用动力学、光谱和反应活性实验来研究来自黄孢原毛霉的MNP和LIP氧化丁香基和愈创木基酚二聚体模型化合物的机理，以及MNP和漆酶形成鳞片藻的机理。此外，还将探讨角叉藻降解非酚类模型化合物的机理。此外，还对LIP氧化苯酚的机理和苯酚抑制LIP氧化非酚类芳香族化合物的机理进行了探讨。最后，利用我们的黄孢霉DNA转化系统，建立了这些过氧化物酶的同源表达系统。木质素是生物圈中第二丰富的天然聚合物，也是最丰富的可再生芳香物质。本研究主要针对降解木质素的真菌及其催化降解木质素的酶的结构和机理进行了研究。利用这些微生物将木质素转化为有用的材料、化学品和燃料是一个非常重要的研究领域。

The aim of the proposed project is to further our understanding of manganese peroxidase (MnP) and lignin peroxidase (LiP) from the lignin-degrading basidiomycete Phanerochaete chrysosporium. The underlying objectives of the proposed project are to further characterize the structure, mechanism and function of these enzymes and to clarify their role in lignin degradation. The binding, stoichiometry and mechanism of manganese oxidation by MnP will be studied by kinetic methods and by optical and NMR spectroscopy. Kinetic, spectroscopic and reactivity experiments also will be used to examine the mechanism of oxidation of syringyl and guaiacyl free phenolic dimeric model compounds by MnP and LiP from P. chrysosporium, and MnP and laccase form Dichomitus squalens. The mechanism of nonphenolic model compound degradation by D. squalens will also be examined. In addition, the mechanism of phenol oxidation by LiP and the mechanism of phenol inhibition of nonphenolic aromatic compound oxidation by LiP will be examined. Finally, using our P. chrysosporium DNA transformation system, a homologous expression system will be developed for these peroxidases. %%% Lignin is the second most abundant natural polymer in the biosphere and the most abundant renewable aromatic material. This research focusses on lignin degrading fungi and the structure and mechanisms of the enzymes responsible for catalyzing the degradation. The potential utilization of these micro organisms for transforming lignin into useful materials, chemicals and fuels is a very significant area of research.