title: The importance of the N-terminal beta-turn in bradykinin antagonists.
abstract: Three peptides, B-10148 (Lys-1-Lys0-Arg1-Pro2-Hyp3-Gly4-Igl5-Ser6- DF5F7-Oic8; where Hyp is trans-4-hydroxyproline, Igl is alpha-(2-indanyl)glycine, F5F is 2,3,4,5,6-pentafluorophenylalanine and Oic is (3aS,7aS)-octahydroindole-2-carboxylic acid), B-10206 (DArg0-Arg1-Pro2-Hyp3-Gly4-Igl5-Ser6-DF 5F7-Nc7G8-Arg9; where Nc7G is N-cycloheptylglycine) and B- 10284 (Arg1-Pro2-Pro3-Gly4-Phe5-Thr6-DTic7-Oic8- NH2; where Tic is 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid), were studied in detail by NMR spectroscopy in 60% CD3OH /40% H2O and modeled by a simulated annealing protocol to determine their solution structure. B-10148, an extremely potent BK B1 receptor antagonist with very high BK B2 receptor antagonist activity, despite lacking a C-terminal Arg, displayed an ideal type II beta-turn from Pro2 to Igl5, as well as a salt bridge between the guanidino group of Arg1 and the carboXylate group of Oic8. B-10206, the most potent B2 antagonist, also displayed an ideal type II beta-turn from Pro2 to Igl5 but secondary structure was not observed at the C-terminal end. The third peptide, B-10284, a des-Arg9 analog with a C-terminal amide and a very potent B2 antagonist, had no definite solution structure. The high activity of these peptides emphasizes the importance of the N-terminal beta-turn and the hydrophobic character at the C-terminus in determining the activity of bradykinin antagonists.
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Miskolzie
authors.forename: L
authors.initials: L
authors.lastname: Gera
authors.forename: J M
authors.initials: JM
authors.lastname: Stewart
authors.forename: G
authors.initials: G
authors.lastname: Kotovych
mesh_terms: D001920:Bradykinin / Q000037:antagonists & inhibitors* / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D008958:Models, Molecular; D009842:Oligopeptides / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation; D013696:Temperature; D014867:Water / Q000378:metabolism; D005466:Fluorocarbons
chemical_list: D001920:Bradykinin; D009842:Oligopeptides; D010455:Peptides; D014867:Water; C427464:B 10148; D005466:Fluorocarbons; C427463:B 10206; C427465:B 10284