A laccase with inhibitory activity against HIV-1 reverse transcriptase from the mycorrhizal fungus Lepiota ventriosospora

An isolation procedure that comprised three ion-exchange chromatography steps on DEAE-cellulose, CM-cellulose, and Q-Sepharose, and one gel-filtration step by fast protein liquid chromatography on Superdex 75 was utilized to isolate a laccase with a molecular mass of 65 kDa from fresh fruiting bodies of the mycorrhizal fungus Lepiota ventriosospora. Laccase activity was adsorbed on both DEAE-cellulose and Q-Sepharose but unadsorbed on CM-cellulose. An overall 26.3-fold of purification was obtained. The enzyme demonstrated an optimum temperature at 60 °C and an optimum pH 4.0. The purified laccase was quite stable at pH range of 3.6–4.4, but only 17.8% of total activity left after 1 h incubating at 60 °C. The ranking of its degradative activity toward aromatic substrates was catechol > hydroquinone > ABTS > 2,6-dimethoxy-phenol. It demonstrated the highest inhibitory activity toward HIV-1 reverse transcriptase with an IC50 value of 0.60 μM among fungal laccaes reported up to now.