The proteolytic enzymes of Aeromonas proteolytica

Abstract

Work by earlier investigators has indicated that the marine bacterium, Aeromonas proteolytica, produces an extracellular endopeptidase and an extracellular aminopeptidase, both of which have been isolated in highly purified forms. The present investigation was undertaken with the objective of extending the available knowledge of the production, isolation, and catalytic properties of these two enzymes. The use of polyacrylamide-gel electrophoresis, a technique not available to earlier workers, permitted a sharp separation of all proteins found in culture filtrates of A. proteolytica on an analytical scale. Seven protein components in the culture filtrates were routinely found, irrespective of the source of organic nutrients present in the growth medium. The relative quantities of these proteins, however, varied dramatically with the source of the organic constituent of the growth medium; variations even in the individual production batch of the soybean protein digest added to the medium caused great differences in the relative quantities of the extracellular proteins produced by the organism. Separations by polyacrylamide-gel electrophoresis revealed that A. proteolytica produces not one, but three, endopeptidases, the presence of two of which had not been previously been suspected. Evidence was further found to suggest that the three endopeptidases are involved in a subunit-aggregate relationship. ...