A Novel Laccase with Potent Antiproliferative and HIV-1 Reverse Transcriptase Inhibitory Activities from Mycelia of MushroomCoprinus comatus

Abstract

A novel laccase was isolated and purified from fermentation mycelia of mushroomCoprinus comatuswith an isolation procedure including 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. The purified enzyme was a monomeric protein with a molecular weight of 64 kDa. It possessed a unique N-terminal amino acid sequence of AIGPVADLKV, which has considerably high sequence similarity with that of other fungal laccases, but is different from that ofC. comatuslaccases reported. The enzyme manifested an optimal pH value of 2.0 and an optimal temperature of 60°C using 2,2′-azinobis(3-ethylbenzothiazolone-6-sulfonic acid) diammonium salt (ABTS) as the substrate. The laccase displayed, at pH 2.0 and 37°C,Kmvalues of 1.59 mM towards ABTS. It potently suppressed proliferation of tumor cell lines HepG2 and MCF7, and inhibited human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) with an IC50value of 3.46 μM, 4.95 μM, and 5.85 μM, respectively, signifying that it is an antipathogenic protein.