@misc{PeterKarichUllrichetal., author = {Peter, Sebastian and Karich, Alexander and Ullrich, Ren{\´e} and Gr{\"o}be, Glenn and Scheibner, Katrin and Hofrichter, Martin}, title = {Enzymatic one-pot conversion of cyclohexane into cyclohexanone: Comparison of four fungal peroxygenases}, series = {Journal of Molecular Catalysis : B, Enzymatic}, journal = {Journal of Molecular Catalysis : B, Enzymatic}, number = {103}, doi = {10.1016/j.molcatb.2013.09.016}, pages = {47 -- 51}, abstract = {Unspecific peroxygenases (UPO; EC 1.11.2.1) represent a group of secreted heme-thiolate proteins that are capable of catalyzing the mono-oxygenation of diverse organic compounds, using only H2O2 as a co-substrate. Here we show that the four peroxygenases AaeUPO, MroUPO, rCciUPO and rNOVO catalyze the stepwise hydroxylation of cyclohexane to cyclohexanol and cyclohexanone. The catalytic efficiencies (kcat/Km) for the initial hydroxylation were in the same order of magnitude for all four peroxygenases (∼104 M-1 s-1), whereas they differed in the second step. The conversion of cyclohexanol by AaeUPO and rCciUPO was 1-2 orders of magnitude less efficient (∼102 M-1 s-1) than by MroUPO and rNOVO (∼104 M-1 s-1). The highest conversion rate in terms of H2O2 utilization was accomplished by MroUPO under repeated addition of the peroxide (87\% in relation to the total products formed). Using the latter UPO, we successfully established a micro-mixing reaction device (SIMM-V2) for the oxidation of cyclohexane. As cyclohexanone is a chemical of high relevance, for example, as starting material for polymer syntheses or as organic solvent, new enzymatic production pathways for this compound are of interest to complement existing chemical and biotechnological approaches. Stable and versatile peroxygenases, as those presented here, may form a promising biocatalytic platform for the development of such enzyme-based processes.}, language = {en} } @misc{KarichScheibnerUllrichetal., author = {Karich, Alexander and Scheibner, Katrin and Ullrich, Ren{\´e} and Hofrichter, Martin}, title = {Exploring the catalase activity of unspecific peroxygenases and the mechanism of peroxide-dependent heme destruction}, series = {Journal of Molecular Catalysis B: Enzymatic}, volume = {134}, journal = {Journal of Molecular Catalysis B: Enzymatic}, number = {A}, issn = {1381-1177}, doi = {10.1016/j.molcatb.2016.10.014}, pages = {238 -- 246}, abstract = {The catalase activity of three unspecific peroxygenases (UPOs) from the agaric basidiomycetes Agrocybe aegerita, Coprinopsis cinerea and Marasmius rotula was investigated. The study included analysis of pH dependency of the catalase reaction and H₂O₂ mediated enzyme inactivation as well as experiments on the influence of a second substrate on the course of catalase reaction. Apparent kinetic parameters (Km, kcat) for the catalase activity of UPOs were determined. Inactivation of UPOs by H₂O₂ is discussed with regard to O₂ production and remaining UPO activity. Furthermore formation of biliverdin as heme destruction product was demonstrated along with the formation of UPO compound III as a possible intermediate that forces the destruction process. Radical trapping experiments with methyl benzoate gave indication for the formation of hydroxyl radicals in the presence of excess H₂O₂. Eventually, a plausible pathway of heme destruction has been proposed, proceeding via UPO compound III and subsequent hydroxyl radical formation, which in turn may cause heme bleaching and verdoheme and biliverdin formation.}, language = {en} } @misc{KarichUllrichScheibneretal., author = {Karich, Alexander and Ullrich, Ren{\´e} and Scheibner, Katrin and Hofrichter, Martin}, title = {Fungal unspecific peroxygenases oxidize the majority of organic EPA priority pollutants}, series = {Frontiers in Microbiology}, volume = {8}, journal = {Frontiers in Microbiology}, issn = {1664-302X}, doi = {10.3389/fmicb.2017.01463}, pages = {15}, abstract = {Unspecific peroxygenases (UPOs) are secreted fungal enzymes with promiscuity for oxygen transfer and oxidation reactions. Functionally, they represent hybrids of P450 monooxygenases and heme peroxidases; phylogenetically they belong to the family of heme-thiolate peroxidases. Two UPOs from the basidiomycetous fungi Agrocybe aegerita (AaeUPO) and Marasmius rotula (MroUPO) converted 35 out of 40 compounds listed as EPA priority pollutants, including chlorinated benzenes and their derivatives, halogenated biphenyl ethers, nitroaromatic compounds, polycyclic aromatic hydrocarbons (PAHs) and phthalic acid derivatives. These oxygenations and oxidations resulted in diverse products and-if at all-were limited for three reasons: (i) steric hindrance caused by multiple substitutions or bulkiness of the compound as such (e.g., hexachlorobenzene or large PAHs), (ii) strong inactivation of aromatic rings (e.g., nitrobenzene), and (iii) low water solubility (e.g., complex arenes). The general outcome of our study is that UPOs can be considered as extracellular counterparts of intracellular monooxygenases, both with respect to catalyzed reactions and catalytic versatility. Therefore, they should be taken into consideration as a relevant biocatalytic detoxification and biodegradation tool used by fungi when confronted with toxins, xenobiotics and pollutants in their natural environments.}, language = {en} } @incollection{HofrichterKellnerHerzogetal., author = {Hofrichter, Martin and Kellner, Harald and Herzog, Robert and Karich, Alexander and Liers, Christiane and Scheibner, Katrin and Kimani, Virginia Wambui and Ullrich, Ren{\´e}}, title = {Fungal Peroxygenases: A Phylogenetically Old Superfamily of Heme Enzymes with Promiscuity for Oxygen Transfer Reactions.}, series = {Grand Challenges in Fungal Biotechnology}, booktitle = {Grand Challenges in Fungal Biotechnology}, editor = {Nevalainen, Helena}, edition = {1. Auflage}, publisher = {Springer Nature}, address = {Cham}, isbn = {978-3-030-29540-0}, issn = {2367-1017}, doi = {10.1007/978-3-030-29541-7}, pages = {369 -- 403}, language = {en} }