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.

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► A laccase from mycorrhizal not white-rot fungus is reported.
► We evaluate its physical, chemical, and bioactive properties.
► It manifests unique amino acid sequence comparing with other laccases.
► It is stable at pH 4.0 after an incubation of 1 h.
► It possesses a very high inhibitory activity toward HIV-1 RT.