@misc{KinnePorajKobielskaUllrichetal., author = {Kinne, Matthias and Poraj-Kobielska, Marzena and Ullrich, Ren{\´e} and Nousiainen, Paula and Sipil{\"a}, Jussi and Scheibner, Katrin and Hammel, Kenneth E. and Hofrichter, Martin}, title = {Oxidative cleavage of non-phenolic b-O-4 lignin model dimers by an extracellular aromatic peroxygenase}, series = {Holzforschung}, volume = {65}, journal = {Holzforschung}, number = {5}, issn = {1437-434X}, doi = {10.1515/HF.2011.057}, pages = {673 -- 679}, abstract = {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 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.}, language = {en} } @misc{PengWollenbergerHofrichteretal., author = {Peng, Lei and Wollenberger, Ulla and Hofrichter, Martin and Ullrich, Ren{\´e} and Scheibner, Katrin and Scheller, Frieder W.}, title = {Bioelectrocatalytic properties of Agrocybe aegerita peroxygenase}, series = {Electrochimica Acta}, volume = {55}, journal = {Electrochimica Acta}, number = {27}, issn = {0013-4686}, doi = {10.1016/j.electacta.2009.12.065}, pages = {7809 -- 7813}, abstract = {A biosensor for detecting the aromatic substance 4-nitrophenol based on Agrocybe aegerita peroxygenase (AaP) immobilized with chitosan-stabilized gold nanoparticles is presented here. This biosensor measures the enzymatic product of 4-nitrophenol peroxygenation, 4-nitrocatechol, which is electrochemically detected in the presence of hydrogen peroxide. Cyclic voltammetry and amperometry were used to characterize the proposed biosensor. The linear range of the AaP biosensor for the detection of 4-nitrophenol was between 10 and 30 μM with a detection limit of 0.2 μM (based on the S/N = 3). The catalytic property of AaP to oxidize 4-nitrophenol was compared with two other heme proteins, a camphor-hydroxylating cytochrome P450 monooxygenase (P450cam, CYP101) and horseradish peroxidase (HRP). The results revealed that only AaP is capable of catalyzing the hydroxylation of 4-nitrophenol into 4-nitrocatechol. Consequently, AaP could be a particularly potent biocatalyst that may fill the gap between cytochrome P450s and common heme peroxidases.}, language = {en} } @misc{FriedrichGroebeKlugeetal., author = {Friedrich, Stephanie and Gr{\"o}be, Glenn and Kluge, Martin and Brinkmann, Tobias and Hofrichter, Martin and Scheibner, Katrin}, title = {Optimization of a biocatalytic process to gain (R)-1-phenylethanol by applying the software tool Sabento for ecological assessment during the early stages of development}, series = {Journal of Molecular Catalysis : B, Enzymatic}, journal = {Journal of Molecular Catalysis : B, Enzymatic}, number = {103}, issn = {1381-1177}, doi = {10.1016/j.molcatb.2013.10.002}, pages = {36 -- 40}, abstract = {Ecological assessment using the software tool Sabento was conducted to compare different processes to gain the fine chemical (R)-1-phenylethanol from ethylbenzene. The software was applied during the biocatalytic process development using the unspecific peroxygenase (EC .11.2.1) of the fungus Agrocybe aegerita. The process could be systematically improved with respect to the ecological performance during process development. Compared to a modern chemical process and a further biotechnological process, it now reaches the best environmental key indicator. The software tool Sabento proved to be well suited to work out the most important factors determining the ecological burdens in the early stages of process development.}, language = {en} } @misc{UllrichNueskeScheibneretal., author = {Ullrich, Ren{\´e} and N{\"u}ske, J{\"o}rg and Scheibner, Katrin and Spantzel, J{\"o}rg and Hofrichter, Martin}, title = {Novel Haloperoxidase from the Agaric Basidiomycete Agrocybe aegerita Oxidizes Aryl Alcohols and Aldehydes}, series = {Applied and Environmental Microbiology}, volume = {70}, journal = {Applied and Environmental Microbiology}, number = {8}, issn = {1098-5336}, doi = {10.1128/AEM.70.8.4575-4581.2004}, pages = {4575 -- 4581}, abstract = {Agrocybe aegerita, a bark mulch- and wood-colonizing basidiomycete, was found to produce a peroxidase (AaP) that oxidizes aryl alcohols, such as veratryl and benzyl alcohols, into the corresponding aldehydes and then into benzoic acids. The enzyme also catalyzed the oxidation of typical peroxidase substrates, such as 2,6-dimethoxyphenol (DMP) or 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS). A. aegerita peroxidase production depended on the concentration of organic nitrogen in the medium, and highest enzyme levels were detected in the presence of soybean meal. Two fractions of the enzyme, AaP I and AaP II, which had identical molecular masses (46 kDa) and isoelectric points of 4.6 to 5.4 and 4.9 to 5.6, respectively (corresponding to six different isoforms), were identified after several steps of purification, including anion- and cation-exchange chromatography. The optimum pH for the oxidation of aryl alcohols was found to be around 7, and the enzyme required relatively high concentrations of H2O2 (2 mM) for optimum activity. The apparent Km values for ABTS, DMP, benzyl alcohol, veratryl alcohol, and H2O2 were 37, 298, 1,001, 2,367 and 1,313 μM, respectively. The N-terminal amino acid sequences of the main AaP II spots blotted after two-dimensional gel electrophoresis were almost identical and exhibited almost no homology to the sequences of other peroxidases from basidiomycetes, but they shared the first three amino acids, as well as two additional amino acids, with the heme chloroperoxidase (CPO) from the ascomycete Caldariomyces fumago. This finding is consistent with the fact that AaP halogenates monochlorodimedone, the specific substrate of CPO. The existence of haloperoxidases in basidiomycetous fungi may be of general significance for the natural formation of chlorinated organic compounds in forest soils.}, language = {en} }