Purification and property of laccase from Pleurotus eryngii var. tuoliensis

An extracellular laccase from the culture broth of Pleurotus eryngii var. tuoliensis 00485 mycelia was isolated and its characterization was determined. The purification procedure was involved in exchange chromatography on DEAE-cellulose, CM-cellulose, and SP-Sepharose, and gel filtration on Superdex 75. The laccase was designed as Pn Lac. SDS-PAGE detection showed Pn Lac was a monmeric protein of 65 k Da. Three amino acid sequences were obtained after tryptic digestion of Pn Lac, and they exhibited some similarity to those of laccases from the mushrooms Pleurotus ostreatus, Lentinus sajur-caju and Pleurotus eryngii by NBCI-BLAST. Its optimum p H and temperature were 3.0 and 50°C for ABTS [2,2′-azinzo-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt], respectively. The laccase activity was inhibited by Ca2+and Hg2+ while increased by Cu2+ and Mn2+. The Km and Vmax values of Pn Lac was 0.17mmol/L and 1.76OD/min/U, respectively.