title: Structural requirements for B2-agonists with improved degradation stability.
abstract: Studies on bradykinin (BK) have been impeded by the fact that this peptide is rapidly degraded by various kininases. Modifications enacted to stabilize the BK sequence have usually resulted in a loss of agonistic activity. In this study, new structural modifications were investigated with the aim to identify degradation-resistant agonists on the bradykinin B2-receptor. The efficacy and degradation stability of several potentially agonistic derivatives were examined using a B2-receptor model (FURA-stained rat fibroblasts) and rat serum kininases. Modifications of the investigated BK analogues included amino-terminal (D-Arg) or carboxy-terminal (Ile-Tyr) prolongation, various substitutions at positions 2, 5, 7, 8 (tetrahydroisoquinoline-3-carboxylic acid, octahydroindole-2-carboxylic acid, hydroxy-proline, beta-2-thienylalanine, 2,3-dehydro-phenylalanine, erythro-beta-phenylserine, erythro-alpha-amino-beta-phenyl-butyric acid, N-methyl-phenylalanine), or intramolecular cyclization via lactam bridges. Kinin inactivation was investigated in rat serum, where the activities of angiotensin I-converting enzyme (ACE), carboxypeptidase N (CPN), aminopeptidase P (APP) and aminopeptidase M (APM) could be differentiated by selective inhibitors. Analogues derived from phyllokinin (BK-Ile-Tyr-SO4) and cyclic peptides had no receptor affinity. Useful modifications compatible with agonistic activity included D-Arg0 (protects against APP), D-N-methyl-Phe7 and dehydro-Phe5 (protect against ACE), and erythro-phenylserine or erythro-amino-phenyl-butyric acid at position 8 (protect against ACE and CPN). Finally, the kinin derivatives D-Arg0-[Hyp3, Thi5, epsilonSer(betaPh)8]-BK and D-Arg0-[Hyp3, Thi5, epsilonAbu(betaPh)8]-BK proved to be potent B2-agonists with extensive stability against rat serum kininases.
authors.affiliation: Institute of Pharmacology, Medical University of Lübeck, Germany. dendorfe@medinf.mu-luebeck.de
authors.forename: A
authors.initials: A
authors.lastname: Dendorfer
authors.forename: M
authors.initials: M
authors.lastname: Wagemann
authors.forename: S
authors.initials: S
authors.lastname: Reissmann
authors.forename: P
authors.initials: P
authors.lastname: Dominiak
mesh_terms: D000818:Animals; D001920:Bradykinin / Q000378:metabolism; D002478:Cells, Cultured; D004351:Drug Resistance; D010450:Endopeptidases / Q000097:blood; D006207:Half-Life; D007705:Kinins / Q000737:chemistry* / Q000378:metabolism*; D018716:Molecular Mimicry; D051381:Rats; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin / Q000819:agonists* / Q000737:chemistry
chemical_list: D007705:Kinins; D043782:Receptor, Bradykinin B2; D018002:Receptors, Bradykinin; D010450:Endopeptidases; C032615:bradykinin kininase; D001920:Bradykinin