Hemostatically Active Proteinase Produced by Aspergillus ochraceus: Key Specific Properties and Effect on Target...

The effect of A. ochraceus proteinase on the proteins of the human hemostasis system, fibrin, fibrinogen, plasminogen, protein C, and factor X, was studied. These proteins are key targets for proteolytic enzymes in therapy and diagnosis of thromboembolic complications. It was shown that A. ochraceus proteinase efficiently cleaves fibrin and fibrinogen, but does not act precisely, since it cuts all three subunits of these proteins. The proteinase did not have an activating effect on the plasminogen, a precursor of plasminogen and plasmin. The proteinase of A. ochraceus was shown to be the first fungal proteinase with proven activating activity towards the human hemostasis system factors protein C and factor X. For protein C activation, A. ochraceus proteinase requires Ca²⁺ ions. The enzyme was found to be sensitive to thrombin inhibitors, but not to plasmin inhibitors. A proteolytic action profile of the scope of this proteinase as a proteinase with activating protein C, factor X, and plasmin-like activity was proposed.