Oxidative cleavage of non-phenolic b-O-4 lignin model dimers by an extracellular aromatic peroxygenase

  • The extracellular aromatic peroxygenase of the agaric fungus Agrocybe aegerita catalyzed the H2O2-dependent cleavage of non-phenolic arylglycerol-b-aryl ethers (b-O-4 ethers). For instance 1-(3,4-dimethoxyphenyl)-2-(2-methoxy-phenoxy)pro- pane-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 18O from H218O2 and H218O at different positions into the products provided information about the routes of ether cleavage. Studies with a 14C-labeled lignin model dimer showed that more than 70% of the intermediates formed were furtherThe extracellular aromatic peroxygenase of the agaric fungus Agrocybe aegerita catalyzed the H2O2-dependent cleavage of non-phenolic arylglycerol-b-aryl ethers (b-O-4 ethers). For instance 1-(3,4-dimethoxyphenyl)-2-(2-methoxy-phenoxy)pro- pane-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 18O from H218O2 and H218O at different positions into the products provided information about the routes of ether cleavage. Studies with a 14C-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 peroxyge- nases may be involved in the bioconversion of methoxylated plant ingredients originating from lignin or other sources.show moreshow less

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Author: Matthias Kinne, Marzena Poraj-Kobielska, René UllrichORCiD, Paula Nousiainen, Jussi Sipilä, Katrin Scheibner, Kenneth E. Hammel, Martin HofrichterORCiD
DOI:https://doi.org/10.1515/HF.2011.057
ISSN:1437-434X
Title of the source (German):Holzforschung
Document Type:Scientific journal article peer-reviewed
Language:English
Year of publication:2011
Tag:0-dealkylation; Agrocybe aegerita; hydroxylation; lignin model compound; peroxidase; peroxygenase
Volume/Year:65
Issue number:5
First Page:673
Last Page:679
Faculty/Chair:Fakultät 2 Umwelt und Naturwissenschaften / FG Enzymtechnologie
Institution name at the time of publication:Fakultät für Naturwissenschaften (eHL) / Prof. Enzymtechnologie
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