[Proteolytic enzymes produced by Aspergillus ochraceus in relation to their plasma coagulating and fibrinolytic activities]

The paper describes some properties of coagulases and fibrinolytic enzymes isolated from a proteolytic complex produced by Aspergillus ochraceus HP-19 during submerged cultivation on a synthetic medium. Proteolytic enzymes with the plasmocoagulating activity hydrolyzed casein at the maximum rate at 45 degrees C and pH 8.0--10.0. The coagulases were stable at pH 5.0--7.0 and were rather resistant to low pH values. The enzymes were entirely inactivated at 55 degrees C within 20--30 min. The activity of the coagulases was inhibited with the ions of Cu, Co, Ag, Pb, Mn, Zn and Hg (1.10(-3) M) by 100, 91, 85, 50, 50, 38 and 25%, respectively. The coagulases were entirely inhibited with EDTA whereas PCMB and PMSF inhibited their activity only to a small extent. The mechanism for blood clotting with the coagulases of Aspergillus ochraceus HP-19 is presumed to consist in the activation of protrombin via its limited specific proteolysis. The fibrinolytic enzymes of Aspergillus ochraceus HP-19 had the optimal pH 8.5 for casein, were stable at pH 6.0, and entirely inactivated at 55 degrees C within 5 min. In contrast to coagulases, they were resistant to the action of heavy metal ions. The enzymes were stabilized by the ions of Ca. The activity of the fibrinolytic enzymes of Aspergillus ochraceus HP-19 was completely inhibited with PMSF. Therefore, they belong to the class of serine proteases.