In vivo inhibition of tissue kallikreins by kininogen sequence analogue peptides

Kininogen sequence analogs containing amino acid residues around the Arg-Ser cleavage site of bovine kininogens were prepared with bulky aliphatic residues in P3 position. KKI-7 (containing a cyclohexylacetyl group) and KKI-8 (containing an adamantaneacetyl group) both inhibited human urinary kallikrein (HUK) with Ki of 4 microM. These inhibitors were 40 times more potent than the corresponding peptide containing the naturally occurring Pro at P3 and were one-seventh as susceptible to hydrolysis by HUK. Rat submaxillary kallikrein (RSK) and porcine pancreatic kallikrein (PPK) were also inhibited by these analogs. Both analogs were poor inhibitors of human plasma kallikrein, while their capacity to inhibit bovine trypsin was 1/3 and 1/17, respectively, that to inhibit HUK. In a rat blood flow study, KKI-7 infusion depressed the response to injected RSK. The response gradually returned toward normal 30 to 60 min after the infusion was terminated. Blood flow increase of dog jejunal artery in response to infused PPK was blunted by the simultaneous local infusion of Trasylol, KKI-7, or KKI-8, whereas these infusions did not alter the response to infused bradykinin. The vehicle infusion did not attenuate the response either to PPK or bradykinin. These analogs appear to have greater specificity and stability than those previously developed and to be appropriate for the in vivo inhibition of glandular kallikreins.