Properties of extracellular proteinase—an activator of protein C in blood plasma formed by Aspergillus ochraceus

The properties of an extracellular proteinase activating plasma protein C isolated from the culture supernatant of Aspergillus ochraceus VKM F-4104D have been studied. This enzyme demonstrated a substrate specificity absent of hydrolyzing activity toward chromogenic proteinase substrates. On the basis of inhibitory analysis, the protein C-activating proteinase from A. ochraceus VKM F-4104D appeared to be a serine proteinase-protein C activator, together with that isolated from the venom of Agkistrodon contortrix contortrix. The isolated enzyme was a nonglycosylated protein with a molecular weight of about 33 kDa, pI 6.0 with an observed optimal activity under a pH of 8.0–9.0 and 37°C. A comparison of the properties of the protein C-activating proteinase formed by A. ochraceus and the enzyme derived from the venom of Agk. contortrix contortrix demonstrated a similarity in their properties; however, proteinase from the micromycete appeared to be in the nonglycosylated state and possessed the ability to hydrolyze the chromogenic plasmin substrate H-D-Val-Leu-Lys-pNA.