Proteolytic systems in the aquatic fungus Allomyces

In the exponentially growing Vegetative cells of Allomyces arbuscula we hav e identified three more enzyme activities using synthetic peptide substrate s. These were in addition to two identified previously as Ca2+-dependent pr oteases (CDP I and CDP II) cleaving peptides at Arg in primary cleavage sit e (P1 position). One of the three new enzymes specifically cleaved peptides at Arg, another at Ala, Leu or Phe and the third preferred Tyr in P1 posit ion. All these activities were Ca2+-independent. The activity showing prefe rence for Ala in P1 position was different from the similar enzyme from dif ferentiating cells since it was not inhibited by the serine protease inhibi tors at concentrations known to inhibit differentiating cell enzyme or tryp sin, both serine proteases. These enzymes were not inhibited by classical p rotease inhibitors.