Soybean trypsin inhibitors inhibit trypsin-like and basic proteinase activities of cultured-fishes

Soybean trypsin inhibitors (SBTI) inhibited trypsin and basic proteinase in the hepatopancreas, pyloric ceaca and intestine of cultured-marine and freshwater fishes. The highest trypsin inhibition by the SBTI was obtained in tiger puffer Takifugu rubripes, followed by rainbow trout Oncorhynchus mykiss, striped jack Pseudocaranx delicatissimus, red sea bream Pagrus major, Japanese striped knifejaw Oplegnathus fasciatus, grouper Epinephelus septemfasciatus, bluefin tuna Thunnus thynnus, purplish amberjack Seriola dumerili, yellowtail Seriola quinqueradiata. The highest basic proteinase inhibition by the SBTI was obtained in red sea bream, followed by rainbow trout, grouper, purplish amberjack, tiger puffer, Japanese striped knifejaw, bluefin tuna, striped jack, yellowtail. These results suggest that the dietary soybean meal utility, being somewhat higher in a rainbow trout, red sea bream, and tiger puffer than yellowtail, do not actually correlate to their sensitivity of trypsin-like and basic proteinase for SBTI.