Kininase of the Latrodectus tredecimguttatus venom: a study of its enzyme substrate specificity.

The specificity of the peptide hydrolyzing action of a highly purified preparation of kininase from Latrodectus Tredecimguttatus venom was studied by the method of TLC on silica gel with the use of various synthetic peptides as substrates. It was shown that the enzyme cleaves the -Pro(7)-Phe(8)-bonds in BK and AI molecules liberating, correspondingly, the C-terminal dipeptide and tripeptide. Exopeptidase specificity was not revealed in the enzyme activity with the use of a number of free and N-substituted tri- and pentapeptides. The results obtained characterize the spider venom kininase as a thiol endopeptidase, which cleaves internal peptide bonds at the proline carboxyl end.