초록
<P>This work reports the production of a novel serine protease enzyme (P. dig‐protease) from the fungus <I>Penicillium digitatum</I>. The protease was purified from the culture supernatant to homogeneity using ammonium sulfate precipitation, Sephadex G‐150 gel filtration and carboxymethyl‐sepharose ion exchange chromatography with a 13‐fold increase in specific activity. The apparent molecular weight of P.dig‐protease was estimated to be 120 kDa by native high performance liquid chromatography (HPLC), sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS–PAGE) revealed a single polypeptide at about 30 kDa that indicates a tetrameric protein. The proteolytic activity was inhibited by phenylmethylsulfonyl fluoride suggesting a serine‐protease enzyme. P.dig‐protease stability was investigated over broad range of pH, temperature, salt concentrations, surfactants and metal ions. The purified P.dig‐protease was used for the production of bioactive peptides. Red scorpionfish (<I>Scorpaena notata</I>) muscle was hydrolyzed with P.dig‐protease in order to obtain peptides with biological activities. Interestingly, the hydrolysate revealed the presence of antioxidant and angiotensin‐I converting enzyme inhibitor peptides.</P>