Partial protease activity characterization of squid (Todaropsis eblanae) mantle

Proteolytic activity in mantle of Todaropsis eblanae was maximum at 40 and 65 degrees C Several peaks of activity were detected over the pH range studied (1.5-9.5), indicating the presence of acidic, neutral and alkaline proteases, depending on the temperature. The substantial enzymic inhibition at acidic pH by the inhibitor trans-epoxysuccinyl-L-leucylamine-4-guanidine butane (E-64) revealed the predominance of lysosomal cysteine proteases (cathepsins) which showed higher activity at 65 degrees C than at 40 degrees C. At 65 degrees C and pH 5.5 metallo-proteases were also detected by the inhibition with phenanthroline. Serine protease activity predominated at neutral pH (higher at 40 degrees C than at 65 degrees C), and cysteine proteases were detected at alkaline pH. There was evidence of cathepsin B and L activity at 65 degrees C and to a lesser degree at 40 degrees C.