The cleavage of the Met-Lys bond in a bradykinin derivative by glandular kallikreins.

The synthetic tridecapeptide Gly-Leu-Met-Lys-Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg was used as a model substrate for horse urinary and porcine pancreatic kallikreins. The Met-Lys bond is hydrolyzed selectively by both enzymes. Oxidation of the methionine residue to sulfoxide made the peptide resistant to both kallikreins. Substitution of either the methionine or lysine residues by norleucine led to peptides in which the Nle-Lys or the Met-Nle bonds, respectively, were susceptible to the urinary kallikrein. The esterolytic and Met-Lys bond-splitting activities of both enzymes were inhibited similarly by phenylmethanesulfonyl fluoride. Both activities of the pancreatic kallikrein were inhibited by the chloromethane derivative Ala-Leu-Lys-CH2Cl. Inhibition by benzamidine of Met-Lys hydrolysis by both kallikreins was observed.