[Conformation-activity relations of des-Arg9-bradykinin. I. Conformation of molecules in solution]

The spatial structure of [des-Arg9]bradykinin, a selective agonist of the B1 type kinin receptors, was studied by means of theoretical conformational analysis. In order to restrict the number of conformations under consideration, we used available data on 1H NMR in (CD3)2SO solution indicating the C-terminal carboxyl group to interact with the guanidine group of Arg1 and the hydroxyl group of Ser6. The calculated set of [des-Arg9]bradykinin low-energy conformations was compared with the 1H NMR data. Four types of conformations were selected, which are consistent with experimental data and serve as sterically reliable models for the preferable three-dimensional structure of [des-Arg9]bradykinin in solution.