Abstract
A purified kininogenase preparation which was homogeneous in disc-electrophoresis and ultracentrifugal analysis was obtained from a guinea pig's coagulating gland by the purification methods of DEAE-cellulose chromatography and Sephadex G-200 gel filtration. The apparent molecular weight of it was estimated to be 31000 by ultracentrifugation and about 40000 by gel filtration, and its isoelectric point was found to be pH 3.4 in electrofocusing analysis with carrier ampholyte. Its amino acid composition was similar to those of the other glandular kallikreins, and it was found to be a glycoprotein containing about 14% of carbohydrates. The kininogenase hydrolyzed N-α-tosyl-L-arginine methyl ester and N-α-benzoyl-L-arginine ethyl ester, having the Km values of 7.80×10-4 and 2.13×10-4 M, respectively. the pH optimum appeared to be 9.0 in the esterolytic response. This enzyme seemed to be rather stable in heat treatment because about 60% of the esterolytic activity was retained after a treatment at 75° for 60 min.