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

AUTOR(ES)

Xu, Feng

FONTE

American Society for Microbiology

RESUMO

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.

Documentos Relacionados

• Laccase-Catalyzed Oxidation of Mn2+ in the Presence of Natural Mn3+ Chelators as a Novel Source of Extracellular H2O2 Production and Its Impact on Manganese Peroxidase
• Aminofluorene-DNA adduct formation in Salmonella typhimurium exposed to the carcinogen N-hydroxy-2-acetylaminofluorene.
• Nonrandom binding of the carcinogen N-hydroxy-2-acetylaminofluorene to repetitive sequences of rat liver DNA in vivo.
• Comparisons of the fidelity of transcription of RNA polymerase I and II following N-hydroxy-2-acetylaminofluorene treatment.
• Preferential binding of the chemical carcinogen N-hydroxy-2-aminofluorene to B-DNA as compared to Z-DNA.