[A secreted trypsin-like proteinase from Yersinia pseudotuberculosis]

A proteolytic enzyme splitting casein and catalyzing the hydrolysis of the ester bond in the synthetic substrate, BAEE, in a trypsin-like manner, has been isolated from the cultural filtrate of Yersinia pseudotuberculosis using ultrafiltration and gel-filtration. The molecular mass of the enzyme is 110 kDa. The rate of hydrolysis is proportional to the enzyme and substrate concentrations which is typical for the kinetics of enzymatic reactions. The Km value for the Y. pseudotuberculosis enzyme is 2.5.10(-3) M. The optimal conditions for the enzymatic reaction are as follows: pH 7.4-8.0 (phosphate buffer) and 37 degrees C. The enzyme is inhibited by phenylmethylsulfonylfluoride and tosyllysinechlormethylketone, the specific inhibitors of serine proteinases and trypsin, respectively. These and literary data on bacterial proteinases are suggestive of their possible role as major factors in bacterial pathogenicity.