Proteolytic enzymes in human saliva and gingiva

: Proteolytic activity was studied in human saliva, gingiva and in other tissues of oral cavity by means of hydrolysis of N-alpha-benzoyl-L-arginine ethyl ester (BAEE), protamine and hemoglobin. Alkaline proteinases were mainly observed in gingiva, leukocytes and in a precipitate of mixed saliva. Acid proteinases (pH 3.5) were localized in submaxillary saliva. In a liquid fraction of saliva maximal proteolytic activity was estimated both at pH 3.5 (by hydrolysis of hemoglobin), at pH 8.0 (hydrolysis of BAEE and protamine) and at pH 9.3 (only in experiments with protamine). The protamine-splitting activity at pH 9.3 was found only in parotid saliva. The optima of the proteolytic enzymes activity were at pH 3.5 (substrate hemoglobin) and at pH 7.5 (substrates protamine and BAEE) in precipitate of mixed saliva and in gingiva. Effects of several inhibitors, chelating agents, thiol-containing substances and metal ions on the proteolytic activity in saliva were studied.