Oxidative cleavage of non-phenolic β-O-4 lignin model dimers by an extracellular aromatic peroxygenase
Oxidative cleavage of non-phenolic β-O-4 lignin model dimers by an extracellular aromatic peroxygenase
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DOI：
10.1515/hf.2011.057
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发表时间：
2011-08-01
期刊：
影响因子：
2.4
通讯作者：
Hofrichter, Martin
中科院分区：
文献类型：
--
作者：
Kinne, Matthias;Poraj-Kobielska, Marzena;Hofrichter, Martin
茶树菇胞外芳香族过氧化酶催化H2 O2依赖的非酚芳基甘油-β-芳基醚（β-O-4醚）裂解。例如，1-（3，4-二甲氧基苯基）-2-（2-甲氧基-苯氧基）丙烷-1，3-二醇，一种代表木质素中主要非酚亚结构的柠檬酸二聚木质素模型化合物，在对甲氧基上选择性O-脱甲基化，得到甲醛和1-（4-羟基-3-甲氧基苯基）-2-（2-甲氧基苯氧基）丙烷-1，3-二醇。后一种化合物的苯酚部分然后被酶促氧化成苯氧基自由基和醌型阳离子，其引发二聚体的自催化裂解和单体如2-甲氧基-1，4-苯醌和取代的丙酸的形成。通过（H_2O_2）-O-18和（H_2O）-O-18在不同位置上的引入，提供了醚裂解途径的信息。用C-14标记的木质素模型二聚体的研究表明，超过70%的形成的中间体进一步偶联形成分子量大于10 kDa的聚合物。结果表明，真菌芳香族过氧合酶可能参与生物转化的甲氧基化的植物成分来源于木质素或其他来源。
The extracellular aromatic peroxygenase of the agaric fungus Agrocybe aegerita catalyzed the H2O2-dependent cleavage of non-phenolic arylglycerol-beta-aryl ethers (beta-O-4 ethers). For instance 1-(3,4-dimethoxyphenyl)-2-(2-methoxy-phenoxy)propane-1,3-diol, a recalcitrant dimeric lignin model compound that represents the major non-phenolic substructure in lignin, was selectively O-demethylated at the para-methoxy group to give formaldehyde and 1-(4-hydroxy-3-methoxyphenyl)-2-(2-methoxyphenoxy)propane-1,3-diol. The phenol moiety of the latter compound was then enzymatically oxidized into phenoxy radicals and a quinoid cation, which initiated the autocatalytic cleavage of the dimer and the formation of monomers such as 2-methoxy-1,4-benzoquinone and phenoxyl-substituted propionic acid. The introduction of O-18 from (H2O2)-O-18 and (H2O)-O-18 at different positions into the products provided information about the routes of ether cleavage. Studies with a C-14-labeled lignin model dimer showed that more than 70% of the intermediates formed were further coupled to form polymers with molecular masses above 10 kDa. The results indicate that fungal aromatic peroxygenases may be involved in the bioconversion of methoxylated plant ingredients originating from lignin or other sources.