Extracellular Proteases of Micromycetes as New Agents for Protein C, Factor X and Plasma Prekallikrein Diagnostics

Background: Many patients deficient in such hemostatic factors as protein C, factor X and prekallikrein have been described and have an associated thrombotic tendency. Some snake venom proteases are used in diagnostics of them. At this time, there are some fungal proteases with activator activity to protein C, factor X and prekallikrein produced by Aspergillus ochraceus and Aspergillus terreus. Aims: Study of applicability of proteases of A. ochraceus and A. terreus for protein C, factor X and prekallikrein determination. Methods: Proteases were obtained from cultural fluids by FPLC. Activity was studied with the chromogenic peptide substrates after preincubation of proteases with human plasma. Results: It was demonstrated the same results with specific activity proteinases of A. ochraceus with commercial diagnostic preparations Protac® (protein C activator from venom of South American copperhead) and RVV-X® (factor X activator from venom of Russell‘s viper). Similar experiments were conducted in the presence of factor X deficient plasma and protein C deficient plasma. It was found that concentration of protein C is identical with Protac® (32,7% ± 5%) diagnostic system and specific activity proteinases of A. ochraceus (31,5% ± 5%). Uniform diagnostics interval was detected with RVV-X® diagnostic system (36,6% ± 4%) and proteinases of A. ochraceus (37,4% ± 4%). A. ochraceus protease did not show any activator activity with human plasma, deficient by prothrombin complex factors and plasma deficient by prothrombin complex factors and by contact phase of coagulation factors. A. terreus protease retained activator activities with chromogenic substrates of protein C and factor Xa with both of these deficient plasmas. Activity of the A. terreus with kallikrein chromogenic substrate showed after preincubation with both plasmas is not reduced. Conclusions: Proteases of A. ochraceus are very perspective for protein C and X factor diagnostics and proteases of A. terreus may be useful for prekallikrein determination.