Metabolism in marine flatfish-IV. Carbohydrate and protein digestion in Atlantic halibut (Hippoglossus hippoglossus L.)

1. 1. A survey of the digestive enzymes present in Atlantic halibut has been carried out. 2. 2. The endoproteases pepsin, chymotrypsin, trypsin and elastase and the exoproteases leucine aminopeptidase and carboxypeptidases a and b were identified together with activity towards casein at pH 4.5-5.3. 3. 3. The main carbohydrase activities were a-amylase and a-glucosidase. 4. 4. Although the activity towards p-nitrophenyl N-acetylglucosaminide, was strong in all zones of the alimentary tract, there were only trace amounts of chitinase activity. 5. 5. With the exception of chymotrypsin and elastase, all hydrolytic enzymes were most active in extracts of pyloric caeca. 6. 6. A comparison has been made between the intestinal glycosidases of halibut and those of rat. © 1987.