Comparative study of substrates of fungal laccase

Coriolus versicolor, Pycnoporus cinnabarinus and Pycnoporus coccineus were grown under conditions to produce extracellular laccase. Prior to estimating enzyme activity, culture fluids were pretreated with catalase to destroy hydrogen peroxide and hence minimize peroxidase activity which might interfere with laccase determinations. Similar trends in enzyme assay were shown when colour reagents contained either syringaldazine or 3-dimethylaminobenzoic acid plus 3-methyl-2-benzothiazolone hydrasone as laccase substrates. Use of 2,2'-azino-bis-(3-ethylbenzothiazoline)-6-sulphonate (ABTS) as laccase substrate showed a different trend which was attributed to peroxidatic activity of the catalase using hydrogen peroxide generated by fungal oxidases. Peroxidatic activity was not observed with the other substrates.