Soluble and immobilized laccase as catalysts for the transformation of substituted phenols

The ability of a laccase from the fungus Rhizoctonia praticola to transform 15 phenolic substrates has been examined. Substrates tested included chlorophenols, methylphenols (cresols) and methoxyphenols. The amount of substrate removed was dependent on the substituent group and position of substitution. Virtually 100% of each of the methoxyphenols was transformed, whereas less than 10% of any of the chlorophenols was transformed. The Rhizoctonia laccase was immobilized by covalent coupling to Celite. Syringic acid and 2,6-dimethoxyphenol were completely removed by the immobilized enzyme both initially and after several repeated incubations. The addition of syringic acid enhanced the transformation of 2,4-dichlorophenol with free and immobilized laccase. There were no substantial differences in the relative activities of the free and immobilized enzyme.