The Effect of pH on the Supply of Digestive Hydrolases in Fish with Different Feeding Habits

Abstract

The effect of pH on the activity of peptidases and glycosidases functioning in the intestine and the supply of these enzymes in five fish species from the Rybinsk Reservoir with different feeding habits (roach Rutilus rutilus, bream Abramis brama, perch Perca fluviatilis, zander Zanderlucioperca, and pike Esox lucius) has been studied. In all fish species, the maximum activity of intestinal caseinolytic peptidases and their provision in the specimens was recorded at pH 9, and that of glycosidases was recorded at pH from 7 to 8. The pH values corresponding to the maximum values of the glycosidase activity were similar to those recommended for assessment of the enzyme activity in the digestive tract of vertebrates; values of peptidases were considerably higher. It is suggested that differences in the effect of pH on the provision of peptidases and glycosidases depend on features of the feeding spectrum of the fish species studied.