KINETICS OF CHEMICALLY-MODIFIED LIGNIN PEROXIDASE AND ENZYMATIC OXIDATION OF AROMATIC NITROGEN-CONTAINING COMPOUNDS

Lignin peroxidase from the white-rot fungus Phanerochaete chrysosporiu m was chemically modified by reductive alkylation with benzyl, naphthy l and anthracyl moieties, thereby increasing its superficial hydrophob icity. The three chemical modifications altered the kinetic behaviour of the enzyme in 10% acetonitrile with four different substrates: carb azole, pinacyanol, pyrene and veratryl alcohol. Benzyl modification of lignin peroxidase increased the catalytic efficiency (k(cat)/K-m,K-ap p) 2.7 times for carbazole oxidation. Thirteen N-containing compounds, including pyrroles, pyridines, and aromatic amines, were tested to de termine whether they could be oxidized by lignin peroxidase in 10% ace tonitrile. All the pyrrole analogues and all the amines tested were ox idized, but none of the pyridine analogous reacted. Some products were isolated and analyzed by high-resolution mass spectrometry. Most were dimers or polymers and, in some cases, these contained oxygen atoms. The possibility of bitumen and petroleum modifications using this enzy me is discussed.