THE DIGESTIVE ENZYMES OF THE PACIFIC BROWN SHRIMP PENAEUS-CALIFORNIENSIS .2. PROPERTIES OF PROTEASE ACTIVITY IN THE WHOLE DIGESTIVE-TRACT

Protease activity in the crude extract of the whole digestive tract from the brown shrimp Penaeus californiensis was found to have the following properties; (1) high halotolerance having maximum activity between 0 and 0.5 M NaCl but 50% maximum activity at 2 M NaCl; (2) optimal activity at 50 degrees C; irreversible inactivation at 60 degrees C; and (3) activity between pH 6 and 10 pH with maximum activity around 8. At least eight bands of activity were observed by using PAGE and agarose gels. Trypsin-like, chymotrypsin-like, carboxypeptidase A and B-like and leucine-aminopeptidase-like activity were detected in crude extract.