A novel laccase from a white rot fungus Abortiporus biennis was purified following a purification scheme involving ammonium sulfate saturation, ion exchange chromatography on DEAE-cellulose, CM-cellulose and Q-Sepharose, and fast protein liquid chromatography-gel filtration on Superdex 75. The molecular mass of the enzyme was 56 kDa estimated by SDS-PAGE. The protein was monomeric with an N-terminal amino acid sequence of AIGPVADLTISNG, which exhibited partial homology to the sequence of laccases from family Polyporaceae, but was different from other families. Its optimal pH was 3.0-4.0, and the optimal temperature was 60 degrees C. The laccase displayed a Km value of 33.5 mu M with ABTS as a substrate at pH 3.5 and 37 degrees C. It demonstrated anti-proliferative activity against Hep G2 and MCF-7 cells with IC50 values of 12.5 mu M and 6.7 mu M, respectively, and exhibited inhibitory activity against HIV-1 reverse transcriptase with an IC50 value of 9.2 mu M. (C) 2011 Elsevier Ltd. All rights reserved.