Purification of a proteinase produced by the bivalve pathogen Vibrio alginolyticus NCMB 1339

Abstract. A proteinase produced by the bivalve pathogen Vibrio alginolyticus NCMB 1339 was purified by preparative isoelectric focusing and gel filtration. Proteinase activity was associated with two components of molecular weights 43000 and 41000 and was toxic to larval Ostrea edulis . Production of this enzyme was maximal during the late exponential phase of growth and it remained stable throughout the stationary phase of growth. At 37°C, activity against azocasein was optimal at pH 7–5. The enzyme was inhibited by mercuric chloride, dithiothreitol and ethylene diamine tetra-acetic acid, but not by pepstatin-A, phenylmethylsulphonyl-fluoride or tosyl-L-lysine chloromethylketone.