A kallikrein-like protease. It preferentially converts human high-molecular-weight kininogen (HK) to bradykinin. Displays broad substrate specificity in vitro, with highest activity toward Boc-Val-Leu-Lys-MCA, Boc-Glu-Lys-Lys-MCA, Boc-Glu(OBzl)-Ala-Arg-MCA, Boc-Val-Pro-Arg-MCA, ZPhe-Arg-MCA and Pro-Phe-Arg-MCA. Has preference for Arg and Lys in position P1 and hydrophobic residues in position P2. Is not toxic to mice. Strongly inhibited by aprotinin, moderately inhibited by secretory leukoprotease inhibitor (SLPI), leupeptin, benzamidine, and phenylmethanesulfonyl fluoride (PMSF), weakly inhibited by urinary trypsin inhibitor, and Kunitz-type soybean trypsin inhibitor and not inhibited by EDTA and alpha-1 protease inhibitor. Optimum pH is 8.5. Submaxillary and sublingual salivary glands. Belongs to the peptidase S1 family. Kallikrein subfamily.