Glandular kallikreins cleave Met-Lys and Arg-Ser bonds in kininogen to release Lys-bradykinin. Preferential cleavage of Arg-|-Xaa bonds in small molecule substrates. Highly selective action to release kallidin (lysyl-bradykinin) from kininogen involves hydrolysis of Met-|-Xaa or Leu-|-Xaa. Monomer. Belongs to the peptidase S1 family. Kallikrein subfamily. Native porcine kallikrein is a monomer. Chains of the pancreatic beta-kallikrein are heterogeneous artifacts of proteolytic degradation during isolation.