A thrombolytic protease named kitamase possessing anticoagulant property was purified from edible and medicinal plant Aster yomena (Kitam.) Honda. Kitamase showed a molecular weight 01 50 kDa by SDS-PAGE and displayed a strong fibrin zymogram lysis band corresponding to the similar molecular mass. The enzyme was active at high temperatures (50 degrees C). The fibrinolytic activity of kitamase was strongly inhibited by EDTA, EGTA, TPCK and PMSF, inhibited by Zn2+. The K-m and V-max values for substrate S-2251 were determined as 4.31 mM and 23.81 mM/mg respectively. It dissolved fibrin clot directly and specifically cleaved the alpha, A alpha and gamma-gamma chains of fibrin and fibrinogen. In addition, kitamase delayed the coagulation time and increased activated partial thromboplastin time and prothrombin time. Kitamase exerted a significant protective effect against collagen and epinephrine induced pulmonary thromboembolism in mice. These results suggest that kitamase may have the property of metallo-protease like enzyme, novel fibrino(geno)lytic enzyme and a potential to be a therapeutic agent for thrombosis. (c) 2014, The Society for Biotechnology, Japan. All rights reserved.