Objective The kinds and activities of proteolytic enzymes of tongue,esophagus,craw,muscular stomach,glandular stomach,duodenum,large intestine,pancreas,liver in digestive system of Buteo buteo were studied to provide basic information for taxonomy and evolvement study of wild birds. Methods The experiment was carried out at 4℃ by using gelatine polyacrylamide gel electrophoresis(G-PAGE) ameliorated by Xu Cunshuan. Results 1.At least 26 kinds of proteolytic enzymes were found in digestive system of Buteo buteo.2.The kinds and activities of proteolytic enzymes in the digestive system of Buteo buteo were affected by pH.The activities of proteolytic enzymes was the weakest in the acid environment and the strongest in the alkaline environment,showing that the activity of the alkaline proteolytic enzymes were stronger than that of the neutral proteolytic enzymes,and that of the acid proteolytic enzymes were weakest.3.Duodenum and pancreas had more kinds and stronger activities of proteolytic enzymes than those in tongue,esophagus and craw in any pH value condition.4.The proteolytic enzymes with 75 and 70?kD molecular weight existed in every organ of digestive system except pancreas and liver in any pH condition.Conclusion The similarity of the kinds and the activities of proteolytic enzymes exist in the organs with similar structure and similar functions. The proteolytic enzyme of 75 and 70?kD molecular weight,whose pH-dependent activity is not obvious,exists widely in digestive system of Buteo buteo.The activity of proteolytic enzyme with 198?kD molecular weight is found in every organ of digestive system under pH 8.5 condition.

Objective The kinds and activities of proteolytic enzymes of organs in the digestive system of Grus grus were studied to provide basic information for the taxonomy and evolvement study of wild birds. Methods The experiment was carried out at 4℃ by using gelatine polyacrylamide gel electrophoresis(G-PAGE) ameliorat. Results 1.Altogether 26 kinds of proteolytic enzymes were found in the digestive system of Grus grus in all pH value conditions.2.The kinds and activities of proteolytic enzymes in the digestive system of Grus grus were affected by pH.The activities of proteolytic enzymes were weakest in the acid environment and strongest in the neutral environment,which shows that the activities of the neutral proteolytic enzymes were stronger than those of the alkaline proteolytic enzymes,and those of the acid proteolytic enzymes were weakest.3.The kinds and activities of proteolytic enzymes of the same organ varied tremendously in different pH value conditions.The proteolytic enzymes of different organs had different optimal pH values.4.Proteolytic enzymes with 19?kD molecular weight existed in every organ of the digestive system except glandular stomach in all pH conditions.Proteolytic enzyme with 66 and 22?kD molecular weight was found in every organ of the digestive system in the neutral environment.Conclusion The optimal pH value of proteolytic enzymes in the digestive system of Grus grus is 7.0.The distribution,activity and pH-dependency of proteolytic enzymes of 66?kD,22?kD,19?kD molecular weight are the important characteristic of proteolytic enzymes in the digestive system of Grus grus.