A unique strong fibrinolytic enzyme (katsuwokinase) in skipjack "Shiokara," a Japanese traditional fermented food.

Katsuwokinase (KK) is a unique fibrinolytic enzyme recently found in skipjack "Shiokara," a Japanese traditional salt-fermented food. A crude enzyme extracted from skipjack Shiokara (Katsuwonus pelamis) showed a very strong fibrinolytic activity above 45 CU/g (fibrin plate method) based on plasmin. KK not only hydrolyzed fibrin but also several synthetic amido substrates, particularly pyro-Glu-Gly-Arg-pNA. The fibrinolytic activity of KK was not affected in the presence of 10% NaCl, was stable in the pH range from 1 to 10 at 37 degrees C for 30 min, and was inhibited by DFP, SBTI, BPTI, and aprotinin but not by epsilon-amino-n-caproic acid and t-4-amino-methylcyclohexane carboxylic acid. The crude enzyme contained at least four kinds of KK, and the major form purified had a pI value of approximately 5.0 and a molecular weight of 35,000. The N-terminal amino acid sequence of 21 residues, I-V-G-G-Y-E-Q-Z-A-H-S-Q-P-H-Q-V-S-L-N-S-G-, had 80% homology with that of trypsin. The fibrinolytic activity of the purified enzyme was approximately 2.6 times greater than that of plasmin by molar ratio, demonstrating its identity as a new and very potent fibrinolytic enzyme.