In Vitro Activation of Trypsinogen and Chymotrypsinogen in the Pancreas of Catfish

Abstract

The conditions for the activation of trypsinogen and chymotrypsinogen in the extract of the pancreas of catfish Paracilurus asotus are described.
The cativation of these zymogens and the stability of the activated enzymes in the extract were in vestigated with respect to temperature, time, pH, and concentrations of Ca²⁺ and activator (porcine enteropeptidase and bovine trypsin). The optimal conditions for zymogen activation were established: Trypsinogen was activated to maximal level by porcine enteropeptidase (100μg⁄ml) at 4°C after 2-3 days in 50 mM Tris_HCL buffe, pH 8.0, containing 50mM CaCl₂. Chymotrypsinogen was activated to maximal level by bovine trypsin (20μg⁄ml) at 4°C after 2-3 days in 50 mM Tris-HCI buffer, pH 8.0, containing 50mM CaCl₂.
Both tryptic and chymotrytic activies observed by activation under the optimal conditions were directly related to the amounts of protein in the extract when the protein concentrations ranged from 0.4 to 3.3mg⁄ml and 0.4 to 1.6mg⁄ml, respectively.
The results indicate that the potential activities of zymogens in the pancreas of catfish can be determined by using the above methods.