Skip to Main Content
Oxidative cleavage of diverse ethers by an extracellular fungal peroxygenaseAuthor(s): Matthias Kinne; Marzena Poraj-Kobielska; Sally A. Ralph; Rene Ullrich; Martin Hofrichter; Kenneth E. Hammel
Source: Journal of biological chemistry. Vol. 284, no. 43 (Oct. 23, 2009): p. 29343-29349.
Publication Series: Miscellaneous Publication
View PDF (812.52 KB)
DescriptionMany litter-decay fungi secrete heme-thiolate peroxygenases that oxidize various organic chemicals, but little is known about the role or mechanism of these enzymes. We found that the extracellular peroxygenase of Agrocybe aegerita catalyzed the H2O2-dependent cleavage of environmentally significant ethers, including methyl t-butyl ether, tetrahydrofuran, and 1,4-dioxane. Experiments with tetrahydrofuran showed the reaction was a two-electron oxidation that generated one aldehyde group and one alcohol group, yielding the ring-opened product 4-hydroxybutanal. Investigations with several model substrates provided information about the route for ether cleavage: (a) steady-state kinetics results with methyl 3,4-dimethoxybenzyl ether, which was oxidized to 3,4-dimethoxybenzaldehyde, gave parallel double reciprocal plots suggestive of a ping-pong mechanism (Km(peroxide), 1.99 ± 0.25 mM; Km(ether), 1.43 ± 0.23 mM; kcat, 720 ± 87 s-1), (b) the cleavage of methyl 4-nitrobenzyl ether in the presence of H218O2 resulted in incorporation of 18O into the carbonyl group of the resulting 4-nitrobenzaldehyde, and (c) the demethylation of 1-methoxy-4-trideuteromethoxybenzene showed an observed intramolecular deuterium isotope effect [(kHkD)obs] of 11.9 ± 0.4. These results suggest a hydrogen abstraction and oxygen rebound mechanism that oxidizes ethers to hemiacetals, which subsequently hydrolyze. The peroxygenase appeared to lack activity on macromolecular ethers, but otherwise exhibited a broad substrate range. It may accordingly have a role in the biodegradation of natural and anthropogenic low molecular weight ethers in soils and plant litter.
- We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
- This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
CitationKinne, Matthias; Poraj-Kobielska, Marzena; Ralph, Sally A.; Ullrich, Rene; Hofrichter, Martin; Hammel, Kenneth E. 2009. Oxidative cleavage of diverse ethers by an extracellular fungal peroxygenase. Journal of Biological Chemistry. 284(43): 29343-29349.
KeywordsWood-decaying fungi, biodegradation, oxidation, chemical reactions, hydrogen peroxide, enzymes, industrial applications, biotechnology, Basidiomycetes, catalysis, ethers, fungi, industrial applications
- Oxidative cleavage of non-phenolic β-O-4 lignin model dimers by an extracellular aromatic peroxygenase
- Stepwise oxygenations of toluene and 4-nitrotoluene by a fungal peroxygenase
- Regioselective preparation of (R)-2-(4-hydroxyphenoxy)propionic acid with a fungal peroxygenase
XML: View XML