LIGNIN PEROXIDASE OXIDATION OF AROMATIC-COMPOUNDS IN SYSTEMS CONTAINING ORGANIC-SOLVENTS

Lignin peroxidase from Phanerochaete chrysosporium was used to study t he oxidation of aromatic compounds, including polycyclic aromatic hydr ocarbons and heterocyclic compounds, that are models of moieties of as phaltene molecules. The oxidations were done in systems containing wat er-miscible organic solvents, including methanol, isopropanol, N,N-dim ethylformamide, acetonitrile, and tetrahydrofuran. Of the 20 aromatic compounds tested, 9 were oxidized by lignin peroxidase in the presence of hydrogen peroxide. These included anthracene, 1-, 2-, and 9-methyl anthracenes, acenaphthene, fluoranthene, pyrene, carbazole, and dibenz othiophene. Of the compounds studied, lignin peroxidase was able to ox idize those with ionization potentials of <8 eV (measured by electron impact). The reaction products contain hydroxyl and keto groups. In on e case, carbon-carbon bond cleavage, yielding anthraquinone from 9-met hylanthracene, was detected. Kinetic constants and stability character istics of lignin peroxidase were determined by using pyrene as the sub strate in systems containing different amounts of organic solvent. Ben zyl alkylation of lignin peroxidase improved its activity in a system containing water-miscible organic solvent but did not increase its res istance to inactivation at high solvent concentrations.