A laccase with anti-proliferative activity against tumor cells from a white root fungus Abortiporus biennis

Abstract 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 °C. The laccase displayed a Km value of 33.5 μM with ABTS as a substrate at pH 3.5 and 37 °C. It demonstrated anti-proliferative activity against Hep G2 and MCF-7 cells with IC 50 values of 12.5 μM and 6.7 μM, respectively, and exhibited inhibitory activity against HIV-1 reverse transcriptase with an IC 50 value of 9.2 μM.