Digestive enzymes in marine species. I. Proteinase activities in gut from redfish (Sebastes mentella), seabream (Sparus aurata) and turbot (Scophthalmus maximus)

Abstract

The proteolytic activities of the digestive tract of three carnivorous fish species (Sebastes mentella, Scophthalmus maximus, Sparus aurata) have been studied. The activity found in the stomach showed a pH optimum of 2.0 for all species, whereas this was in the alkaline range (9.5-10.0) in the intestinal extracts. Similar optimal temperature was measured for all species, although higher residual activities were detected at low temperatures in redfish and turbot. Lower E a values were detected in stomach than in intestine. The effect of NaC1 concentration on protein digestion differed between stomach and intestine being inhibitory in the former. The main proteolytic enzyme for the acid activity of the stomach of the three species seemed to be a pepsin. However, the enzymatic composition of the intestine was more species specific