NMR studies of bradykinin and an antibacterial peptide analogue

Abstract

Solution conformations of bradykinin and TEL were studied by NMR. Bradykinin is a peptide hormone which functions as a vasodilator and a pain mediator. TEL is an analogue of C-terminal fragment of Tenecin 1 which exhibits antibacterial activity. All spectra were recorded in $H_2O$/TFE-$d_3$ (1:1 by volume). Although the sequence of bradykinin exhibited high propensity of turns, there was only weak NOE evidence of a turn. Its amide protons, however, proved to be somewhat shielded from solvent from temperature variation experiment. Furthermore, the probability of turns was confirmed by chemical shift difference method. In spite of its high proline content (30\%), bradykinin did not show significant cis-peptide bond populations. TEL did not show any particular NOE patterns of secondary structure. Temperature variation experiment and chemical shift difference method further approved that TEL was in ensemble of many conformers.