Enzymatic properties of the purified extracellular protease of Aeromonas salmonicida, Ar-4 (EFDL)

Abstract

In a previous paper, we examined the toxicity of the extracellular protease of A. salmonicida, Ar-4 (EFDL) on yamabe (Oncorhynchus masou F. ishikawai) and goldfish (Carassius auratus). From these results, we considered the protease secreted by this bacterium was a causative agent of furunculosis. In this paper, we observed enzymatic properties of the purified protease. The results obtained were summarized as follows: 1.The molecular weight of purified protease was estimated to be 71,000 by sodium dodecyl sulfate polyacrylamide gel electrophoresis. 2. The purified protease showed maximal activity at pH 9.4 and 50°C. It was stable over the pH range 5.0 to 10.0 and was completely inactivated by temperature at 56°C. 3. The protease was presumably classified an alkaline serine protease and it showed chymotryptic properties since it was significantly inhibited by diisopropylfluorophosphate (DFP) and tosyl-phenylalanine-chloromethyl ketone (TPCK) and hydrolyzed N-benzoyl-L-tyrosine ethyl ester (BTEE). © 1984, The Japanese Society of Fisheries Science. All rights reserved.