Lignin Peroxidase Oxidation of Aromatic Compounds in Systems Containing Organic Solvents

Abstract

Lignin peroxidase from Phanerochaete chrysosporium was used to study the oxidation of aromatic compounds, including polycyclic aromatic hydrocarbons and heterocyclic compounds, that are models of moieties of asphaltene molecules. The oxidations were done in systems containing water-miscible organic solvents, including methanol, isopropanol, N,N-dimethylformamide, 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-methylanthracenes, acenaphthene, fluoranthene, pyrene, carbazole, and dibenzothiophene. Of the compounds studied, lignin peroxidase was able to oxidize those with ionization potentials of <8 eV (measured by electron impact). The reaction products contain hydroxyl and keto groups. In one case, carbon-carbon bond cleavage, yielding anthraquinone from 9-methylanthracene, was detected. Kinetic constants and stability characteristics of lignin peroxidase were determined by using pyrene as the substrate in systems containing different amounts of organic solvent. Benzyl alkylation of lignin peroxidase improved its activity in a system containing water-miscible organic solvent but did not increase its resistance to inactivation at high solvent concentrations.

Biocatalytic Oxidation of Polycyclic Aromatic Hydrocarbons by Hemoglobin and Hydrogen Peroxide

“…Enzymatic catalysis in organic solvent is an emerging technology that is suited to modification of hydrophobic substrates such as PAH's. Enzymatic and non enzymatic hemoproteins have been proposed as biocatalyst for non aqueous systems (4,17,(18)(19)(20)(21)(22).…”

Removal of polycyclic aromatic hydrocarbons from soil using surfactant and the white rot fungusPhanerochaete chrysosporium

“…Direct oxidation of PAH by in vitro incubations with LiP and with MnP has been reported 21. 22 Lignin peroxidase can oxidize compounds with an ionization potential (IP) ≤ 8.0eV,23, 24 and the oxidized co‐factor of MnP, Mn(III), has been shown to oxidize PAH with IP values ≤ 7.8 eV 23. 25 Manganese peroxidase can also oxidize PAHs, such as phenanthrene, with higher IP values (8.2eV) when co‐incubated with unsaturated lipids via an MnP‐mediated lipid peroxidation‐based oxidation mechanism 26…”

Expression of lip genes during growth in soil and oxidation of anthracene by Phanerochaete chrysosporium

“…To date, most work has centered around one species, Phanerochaete chrysosporium. Biochemical data (1,23,26,36,54), liquid culture studies (1,6,24,25,46), and bench-scale solid-phase experiments (20,37,41,50) have demonstrated the ability of this species and its extracellular ligninolytic enzymes to degrade numerous PAHs. Field-scale trials of a related species, Phanerochaete sordida, have shown promise for remediation of PAH-contaminated sites (10,31).…”