Probing the topological arrangement of the N- and C-terminal residues of bradykinin for agonist activity at the B1 receptor.
The conformational features of H-Lys-Arg-Ado-Ser-Pro-Phe-OH (Ado = 12-aminododecanoic acid), a des-Arg(9) analogue of Lys-bradykinin, have been determined by high-resolution NMR in the presence of a zwitterionic lipid environment. The analogue is the most active member of a series of analogues designed to probe the topological arrangement of the N- and C-termini required for agonistic activity at the B1 kinin receptor. A novel computational procedure for the utilization of NOE constraints from cis and trans configurational isomers is illustrated. Only with this computational methodology could the structural features of the N-terminus of the peptide be determined. Using radical-induced relaxation of the (1)H NMR signals, we measured the topological orientation of the peptide with respect to the zwitterionic lipid interface. The results indicate that the long, alkyl chain of the Ado amino acid imbeds into the lipid surface. The structural features of the C-terminus of the B1-selective analogue consist of a well-defined turn. Although removed from a standard beta-turn, required for activity at the B2 kinin receptor, the topological orientation of the side chains of the des-Arg(9) compound are surprisingly similar to those previously observed for beta-turn-containing bradykinin analogues. Therefore, we attribute the high B1 receptor selectivity, observed upon removal of Arg(9) from bradykinin, solely to the loss of a charged amino acid and not to altered structural features.
Pellegrini
M
M
Department of Molecular Pharmacology, Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912, USA.
Tancredi
M
M
Rovero
P
P
Mierke
D F
DF
D007609:Kallidin / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008567:Membranes, Artificial; D008823:Micelles; D008958:Models, Molecular; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D011487:Protein Conformation; D043783:Receptor, Bradykinin B1; D018002:Receptors, Bradykinin / Q000819:agonists*
D008055:Lipids; D008567:Membranes, Artificial; D008823:Micelles; D009842:Oligopeptides; D043783:Receptor, Bradykinin B1; D018002:Receptors, Bradykinin; C121216:lysyl-arginyl-12-aminodecanoyl-seryl-prolyl-phenylalanine; D007609:Kallidin