Activation, Inhibition, and pII-Dependence of the Hydrolysis of α-N-Benzoyl-L-Arginine Ethyl Ester Catalyzed by Kallikrein from Porcine Pancreas.

Kallikrein from porcine pancreas is inhibited by heavy metal ions and activated by sulfhydryl compounds or chelating agents. This activation is interpreted as a reversal of heavy metal inhibition. From the experiments the conclusion is drawn that kallikrein is neither a "sulfhydryl protease" nor a metal-dependent protease. The pH dependency of the hydrolysis of α-N-benzoyl-L-arginine ethyl ester by kallikrem at low substrate concentrations indicates three basic groups with pK 7.9 and 5.7 in the free enzyme and pK 6.9 in the enzyme-substrate complex winch participate m catalysis. The pH-dependence resembles trypsin- and especially cholinesterase-catalyzed hydrolyses. From the most alkaline pK value the participation of an amino group and from the other pK values the participation of a histidine residue in kallikrein-catalyzed hydrolysis is inferred. [ABSTRACT FROM AUTHOR]