Conversion of dibenzothiophene by the mushrooms Agrocybe aegerita and Coprinellus radians and their extracellular peroxygenases

Abstract

The conversion of the heterocycle dibenzothiophene (DBT) by the agaric basidiomycetes Agrocybe aegerita and Coprinellus radians was studied in vivo and in vitro with whole cells and with purified extracellular peroxygenases, respectively. A. aegerita oxidized DBT (110 microM) by 100% within 16 days into eight different metabolites. Among the latter were mainly S-oxidation products (DBT sulfoxide, DBT sulfone) and in lower amounts, ring-hydroxylation compounds (e.g., 2-hydroxy-DBT). C. radians converted about 60% of DBT into DBT sulfoxide and DBT sulfone as the sole metabolites. In vitro tests with purified peroxygenases were performed to compare the product pattern with the metabolites formed in vivo. Using ascorbic acid as radical scavenger, a total of 19 and seven oxygenation products were detected after DBT conversion by the peroxygenases of A. aegerita (AaP) and C. radians (CrP), respectively. Whereas ring hydroxylation was favored over S-oxidation by AaP (again 2-hydroxy-DBT was identified), CrP formed DBT sulfoxide as major product. This finding suggests that fungal peroxygenases can considerably differ in their catalytic properties. Using H(2)(18)O(2), the origin of oxygen was proved to be the peroxide. Based on these results, we propose that extracellular peroxygenases may be involved in the oxidation of heterocycles by fungi also under natural conditions.

Conversion of polycyclic aromatic hydrocarbons, methyl naphthalenes and dibenzofuran by two fungal peroxygenases

“…strain (Chupungarsa et al 2009)-AaP did not produce 9-fluorenol or 9-fluorenone. This behavior resembles own previous observations (Aranda et al 2009) regarding the conversion of dibenzothiophene (DBT) in vivo and in vitro by both fungi and their peroxygenases: AaP favored the hydroxylation of the aromatic rings of DBT whereas CrP favored the oxidation of the sulphur.…”

“…Both enzymes were found to introduce oxygen functionalities into aromatic rings, although the efficiency of AaP was considerably higher than that of CrP. In recent studies on these peroxideconsuming enzymes, we have demonstrated that the origin of oxygen transferred to the substrate molecule is in fact the peroxide Aranda et al 2009). These results were obtained using 18 O 2 -labeled hydrogen peroxide (H 2 18 O 2 ) as well as naphthalene and dibenzothiophene as substrates.…”

“…Monooxygenases of the P450 type have been proposed as oxygenating biocatalysts which transfer one O-atom from dioxygen to the C 9 of Flu (Pothuluri et al 1993). A similar mechanism may also apply to CrP, that was shown to transfer peroxide-oxygen to polycyclic substrates (Aranda et al 2009). It is interesting to note thatcontrary to a recently published report on Flu metabolism by an Agrocybe sp.…”

“…This designation has recently been coined because of the enzyme's ability to catalyze the epoxidation, hydroxylation and hetero-atom oxygenation of aromatic and heterocyclic rings. For example, APO of Agrocybe aegerita is able to perform the sulfoxidation and hydroxylation of dibenzothiophene (Aranda et al 2009), the ring and side-chain hydroxylation of toluene (Ullrich and Hofrichter 2005), the N-oxidation of pyridine (Ullrich et al 2008) as well as the selective epoxidation of naphthalene ). APO enzymes are secreted heme-thiolate proteins which have been described in detail just for two agaric basidiomycetes, A. aegerita and Coprinellus radians colonizing wood, mulch and dung (Ullrich et al 2004;Anh et al 2007), but there are molecular indications for their wide-spread occurrence in the fungal kingdom and even beyond that (Pecyna et al 2009).…”

Katalytische, milde und selektive Oxyfunktionalisierung von linearen Alkanen: aktuelle Herausforderungen

“…[76][77][78][79][80][81][82][83] Diese H 2 O 2 -abhängigen Häm-Eisenthiolatproteine sind lçslich, bestehen aus nur einer Komponente und vereinen die charakteristischen Eigenschaften von CYPs (Sauerstoffübertragung) mit denen der Peroxidasen, wie z. B. der Häm-Chlorperoxidase (CPO) des Schlauchpilzes Caldariomyces fumago [84] (Phenoloxidation, Halogenoxidation usw.).…”