The haloperoxidase of the agaric fungus Agrocybe aegerita hydroxylates toluene and naphthalene.
The mushroom Agrocybe aegerita secretes a peroxidase (AaP) that catalyzes halogenations and hydroxylations. Phenol was brominated to 2- and 4-bromophenol (ratio 1:4) and chlorinated to a lesser extent to 2-chlorophenol. The purified enzyme was found to oxidize toluene via benzyl alcohol and benzaldehyde into benzoic acid. A second fraction of toluene was hydroxylated to give p-cresol as well as o-cresol and methyl-p-benzoquinone. The UV-Vis absorption spectrum of purified AaP showed high similarity to a resting state cytochrome P450 with the Soret band at 420 nm and additional maxima at 278, 358, 541 and 571 nm; the AaP CO-complex had a distinct absorption maximum at 445 nm that is characteristic for heme-thiolate proteins. AaP regioselectively hydroxylated naphthalene to 1-naphthol and traces of 2-naphthol (ratio 36:1). H2O2 was necessarily required for AaP function and hence the hydroxylations catalyzed by AaP can be designated as peroxygenation and the enzyme as an extracellular peroxygenase.
Ullrich
René
R
Unit of Environmental Biotechnology, International Graduate School of Zittau, Markt 23, 02763 Zittau, Germany. ullrich@ihi-zittau.de
Hofrichter
Martin
M
D000363:Agaricales / Q000201:enzymology*; D005656:Fungal Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D006219:Halogens / Q000737:chemistry; D006900:Hydroxylation; D009281:Naphthalenes / Q000737:chemistry* / Q000378:metabolism; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D010636:Phenols / Q000737:chemistry; D014050:Toluene / Q000737:chemistry* / Q000378:metabolism; D014867:Water / Q000737:chemistry
D005656:Fungal Proteins; D006219:Halogens; D009281:Naphthalenes; D010636:Phenols; D014867:Water; C031721:naphthalene; D014050:Toluene; D009195:Peroxidase