Structure-activity relationships of bradykinin potentiating peptides

A number of A-VI-5 (Val-Glu-Ser-Ser-Lys) analogues and fragments were synthetized and tested on bradykinin potentiating activity so as to establish the nature of the active group(s) or structural characteristics of some bradykinin potentiating pentapeptides. It could be concluded that (1) the polar groups of the side-chains, such as the two hydroxyl groups of the serine residues, the omega-carboxyl group of the glutamic acid residue and the omega-amino group of the C-terminal lysine, are not essential for the bradykinin potentiating activity; (2) the chain length (at least 5 amino acids) and the lipophilicity of the N-terminal amino acid as well as the whole peptide are of much more importance; (3) the free N-terminal NH2-group is not essential; (4) aromatic amino acids in position 3 of the peptide chain result in highly active bradykinin potentiating peptides.