Conformational features of bradykinin. A circular dichroism study of some peptide fragments and structural analogues of bradykinin.

The vasoactive hormone bradykinin, its N-and C-terminal fragments and some structural analogues were studied by Circular Dichroism. Conformational features of the peptide can be detected by comparative analysis of the various CD spectra recorded as a function of aqueous pH, solvent and temperature. It is shown that the two biologically essential arginine residues (Arg1 and Arg9) are important for the specific folded bradykinin conformation. Differences between bradykinin, its fragments and analogues become clearly established in conformational terms, and are discussed in relation to the biological activity of these peptides.