The secretory nature of the excretory gland cells of Strephanurus dentatus. 3. Proteinase inhibitors

A proteinase inhibitor(s) was found in extracts of the excretory gland cells, intestines, esophagi, reproductive organs, and body walls from Stephanurus dentatus adults. The specific activity of the inhibitor(s) in the excretory gland cell extract was 45–175 times greater than in the other tissues. It is heat stable at pH 5.0 and inhibits the esterolytic activity of trypsin and chymotrypsin using p-toluenesulfonyl-l-arginine methyl ester hydrochloride (TAME) and benzoyl-l-tyrosine ethyl ester (BTEE) as the substrates, respectively, and also the proteolytic activity of both chymotrypsin and trypsin using casein as the substrate. S. dentatus adults maintained in NCTC 109 medium, secreted a trypsin inhibitor.