EN
A protease with a molecular mass of 30 kDa and the N-terminal sequence of GLQTNAPWGLARSS, was isolated from fresh fruiting bodies of the wild edible mushroom Termitomyces albuminosus. The purification protocol included ion exchange chromatography on DEAE-cellulose, Q-Sepharose, SP-Sepharose and FPLC-gel filtration on Superdex 75. The protein was unadsorbed on DEAE-cellulose and Q-Sepharose, but adsorbed on SP-Sepharose. The optimal pH and temperature of the purified enzyme were 10.6 and 60°C, respectively. The enzyme was stable in the presence of 2% (v/v) Tween 80 and 4 M urea. More than 80% of the enzyme activity was retained in 2% (v/v) Triton X 100, 54% in 10 mM EDTA and 31% in 2% (w/v) SDS. The enzyme was strongly inhibited by phenylmethylsulfonyl fluoride (PMSF), but not inhibited by dithiothreitol (DTT), pepstatin or lima bean trypsin inhibitor suggesting that it was a serine protease but not a trypsin-like one. The protease was inhibited by Hg2+, Cu2+, and Fe3+ ions. The Km and Vmax values of the purified enzyme for casein were 8.26 mg∙ml−1 and 0.668 mg∙ml−1∙min−1, respectively.