IngentaConnect Oxidation of polycyclic aromatic hydrocarbons catalyzed by soybea...

Authors: Kraus, Jennifer¹; Munir, Inmar¹; McEldoon, James¹; Clark, Douglas²; Dordick, Jonathan³

Source: Applied Biochemistry and Biotechnology, Volume 80, Number 3, June 1999 , pp. 221-230(10)

Abstract:

Soybean peroxidase (SBP) catalyzes the oxidation of a variety of polycyclic aromatic hydrocarbons (PAHs) in the presence of water-miscible organic cosolvents, including acetonitrile, tetrahydrofuran, and dimethylformamide (DMF). Oxidation was optimal at pH 2.0-2.5, with substantially lower reactivity at pH 1.5 as well as at pH > 3.0. Despite the low pH activity optimum, SBP had an observed half-life of 120 h at pH 2.5. Conversions of greater than 90% were observed with anthracene and 9-methylanthracene in the presence of 50% (v/v) DMF. Anthracene oxidation yielded exclusively anthraquinone, thereby demonstrating that SBP catalyzes a formal six-electron oxidation of the unactivated aromatic substrate to the quinone. A mechanism is proposed to account for this reaction that includes the initial one-electron oxidation of the PAH followed by addition of water to the oxidized PAH. 9-Methylanthracene was more reactive than anthracene, and its enzymatic oxidation yielded two products: anthraquinone and 9-methanol-9,10-dihydroanthracene. The former product indicates that loss of the methyl group occurs during enzymatic oxidation. These results suggest that SBP could be useful in the conversion of PAHs into more environmentally benign materials.

Keywords: Peroxidase; oxidation of polycyclic aromatic hydrocarbons; water-miscible organic cosolvents; anthracene

Document Type: Research article

DOI: 10.1385/ABAB:80:3:221

Affiliations: 1: Department of Chemical and Biochemical Engineering, University of Iowa, 52242, Iowa City, IA, 2: Department of Chemical Engineering, University of California, 94720, Berkeley, CA, 3: Department of Chemical and Biochemical Engineering, University of Iowa, 52242, Iowa City, IA, Email: dordick@rpi.edu

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Oxidation of polycyclic aromatic hydrocarbons catalyzed by soybean peroxidase