Laccase from a tree legume, Leucaena leucocephala, was purified to homogeneity using a quick two-step procedure: alginate bead entrapment and celite adsorption chromatography. Laccase was purified 110.6-fold with an overall recovery of 51.0% and a specific activity of 58.5 units/mg. The purified laccase was found to be a heterodimer (similar to 220 kDa), containing two subunits of 100 and 120 kDa. The affinity of laccase was found to be highest for catechol and lowest for hydroquinone, however, highest K-cat and K-cat/K-m were obtained for hydroquinone. Purified laccase exhibited pH and temperature optima of 7.0 and 80 degrees C, respectively. Mn2+, Cd2+, Fe2+, Cu2+ and Na+ activated laccase while Ca2+ treatment increased laccase activity up to 3 mM, beyond which it inhibited laccase. Co2+, Hg2+, DTT, SDS and EDTA showed an inhibition of laccase activity. The Leucaena laccase was found to be fairly tolerant to organic solvents; upon exposure for I h individually to 50% (v/v) each of ethanol, DMF, DMSO and benzene, more than 50% of the activity was retained, while in the presence of 50% (v/v) each of methanol, isopropanol and chloroform, a 40% residual activity was observed. The purified laccase efficiently decolorized synthetic dyes such as indigocarmine and congo red in the absence of any redox mediator. (C) 2014 Elsevier Ltd. All rights reserved.