Identification of a new serine protease from polychaeta, Marphysa sanguinea, for its thrombolytic and anticoagulant activity

A serine protease was purified from Marphysa sanguinea through ammonium sulfate followed by ion exchange chromatography, and its N-terminal amino sequence was identified to be IVGGSEATPYQFPFQ. Fibrinolytic activity was depended on both direct fibrinolysis and indirect plasminogen-mediated cascade and had a consistent activity irrespective of pH. The serine protease could be confirmed to degrade alpha-, beta-, and gamma-chains of human fibrinogen through fibrinogenolytic assay and did not express significant cytotoxicity to endothelial cells. These imply the enzyme has anticoagulant as well as thrombolytic activity, not significantly impairing endothelial cells comprising brain blood brain barrier (BBB) tissue. Conclusively, the new serine protease is worthy of being a candidate to substitute tissue-Plasminogen Activator (t-PA) for acute ischemic reperfusion injury of brain.