Purification and Characterization of Cathepsin L-Like Enzyme from the Muscle of Anchovy, Engraulis japonica

Results relative to inhibitory effects and substrate specificity indicated that a protease from the muscle of anchovy, Engraulis japonica, was a cathepsin L-like enzyme. The enzyme was activated by thiol reagents and inhibited by thiol-blocking reagents. The molecular weight was estimated to be 25.8 kDa by SDS-PAGE. The enzyme exhibited its maximal activity at pH 6.0 and 50°C for casein and N-benzoyl-d, l-arginine-β-naphthylamide. The enzyme hydrolyzed at the position of Phe1, Asn3, Val13, Glu14, Val19 and Gly24 of the insulin β-chain. The K′m and kcat of the enzyme were 73.4 μM and 0.5 μM/min, respectively, toward Z-Phe-Arg-MNap.