NMR investigations of recombinant 15N/13C/2H-labeled bradykinin bound to a Fab mimic of the B2 receptor.

NMR spectroscopy has been used to obtain structural information on the bioactive conformation of the nonapeptide hormone bradykinin (Arg-Pro-Pro-Gly-Ser-Pro-Phe-Arg, BK) bound to the Fab-fragment of an antibody that mimics the hormone binding site of the natural bradykinin B2-receptor. Using 15N or 15N,13C, 60% 2H isotope labelled bradykinin, complete 1H, 13C and 15N assignments for bradykinin bound to the Fab-fragment have been obtained. Preliminary interpretation of 15N edited NOE spectra indicates that the conformation of bradykinin bound to the model receptor differs substantially from previous computer models of the bioactive conformation of bradykinin.