Effect of pH on the activity of digestive enzymes in Silurus asotusin Jialing River

This experiment was conducted to study the effect of pH on the activity of digestive enzymes in stomach,intestine and hepatopancreas of Silurus asotus by means of enzymology analysis.The results showed that the activities of all digestive enzymes in S.asotus increased at first and then decreased with pH increasing in the designed pH ranges.The optimum pH in stomach,intestine and hepatopancreas were 2.2,7.0 and 7.4 respectively for protease,all 7.0 for amylase,7.0,7.0 and 7.4 respectively for lipase.The optimum pH of all digestive enzyme were neutral or weak alkaline except that of pepsin was acidic.It showed that the activities of digestive enzymes in S.asotus had organic specificity.Under optimum pH,the activity of protease in different organs was in the order of anterior intestinehepatopancreasstomachmiddle intestineposterior intestine,and the activity of amylase and lipase were hepatopancreasstomachanterior intestinemiddle intestineposterior intestine.Results showed that there were significant differences among different pH of the same digestive enzyme activity in the same place,and there were also significant differences of the same digestive enzyme activity among different digestive organs in their respective optimum pH.