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Redox Chemistry in Laccase-Catalyzed Oxidation of N-Hydroxy Compounds

By Feng Xu, Juozas J. Kulys, Kyle Duke, Kaichang Li, Kastis Krikstopaitis, Heinz-Josef W. Deussen, Eric Abbate, Vilija Galinyte and Palle Schneider

Abstract

1-Hydroxybenzotriazole, violuric acid, and N-hydroxyacetanilide are three N-OH compounds capable of mediating a range of laccase-catalyzed biotransformations, such as paper pulp delignification and degradation of polycyclic hydrocarbons. The mechanism of their enzymatic oxidation was studied with seven fungal laccases. The oxidation had a bell-shaped pH-activity profile with an optimal pH ranging from 4 to 7. The oxidation rate was found to be dependent on the redox potential difference between the N-OH substrate and laccase. A laccase with a higher redox potential or an N-OH compound with a lower redox potential tended to have a higher oxidation rate. Similar to the enzymatic oxidation of phenols, phenoxazines, phenothiazines, and other redox-active compounds, an “outer-sphere” type of single-electron transfer from the substrate to laccase and proton release are speculated to be involved in the rate-limiting step for N-OH oxidation

Topics: Enzymology and Protein Engineering
Publisher: American Society for Microbiology
Year: 2000
OAI identifier: oai:pubmedcentral.nih.gov:101453
Provided by: PubMed Central
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