Purification and characterization of a novel metalloprotease from fruiting bodies of Oudemansiella radicata

Abstract

In this study, a 39-kDa metalloprotease was purified from a rare health-promoting edible mushroom Oudemansiella radicata using a purification protocol which entailed anion exchange chromatography on DEAE-cellulose and Q-Sepharose columns and gel filtration by fast protein liquid chromatography on Superdex 75 column. Some peptide sequences were determined by LC-MS/MS analysis and one of the sequences, DAWIQADVNR, manifested 90% identity to Coprinopsis cinerea metalloprotease. The optimal reaction pH and temperature for Oudemansiella radicata protease were pH 7.0 and 50℃, respectively. The protease was purified 79-fold and demonstrated a specific protease activity of 2.42 U/mg. The Km of the purified protease for casein was 0.65 mg/mL at pH 7.0 and 50 ℃.The activity of the protease was inhibited by Cd²⁺、Hg²⁺、Cu²⁺、Pb²⁺ and Fe³⁺ ions, and was enhanced by K⁺ ions. The activity of Oudemansiella radicata protease was strongly suppressed by EDTA, indicating that it is a metalloprotease.