A novel fibrin(ogen)olytic protease from Antheraea pernyi (important economically insect), named cocoonase, was isolated by a combination of ion-exchange chromatography and gel filtration. Furthermore, the characterization of cocoonase was investigated using fibrin(ogen)olytic, thrombolysis, and hemorrhagic assays. The NH2-terminal sequence (IVGGY SVTID KAPYQ) was established by Edman degradation. Based on the N-terminal sequencing, cocoonase cDNA has been cloned by means of RT-PCR and 5'RACE. It is composed of 261 amino acid residues and possesses the structural features of trypsin-like serine protease. The purified cocoonase showed specific esterase activity on N-beta-benzoyl-L-arginine ethyl (BAEE), and the kinetic constants, Km and Vmax were 2.577 x 10(-3) mol/L and 4.09 x 10(-3) mu mol/L/s, respectively. Cocoonase showed strong activities on both fibrin and fibrinogen, preferentially hydrolyzed A alpha and B beta chains followed by gamma-chains of fibrinogen. Cocoonase exhibited a thrombolysis activity both in vitro (blood-clot lysis activity assay) and in vivo (carrageenan-induced thrombosis model). These findings indicate that A. pernyi cocoonase ia a novel fibrin(ogen)olytic enzyme and may have a potential clinical application as an antithrombotic agent. (C) 2014 Elsevier Inc. All rights reserved.