Nmr and molecular modeling investigations of the neuropeptide bradykinin in three different solvent systems: DMSO, 9 : 1 dioxane/water, and in the presence of 7.4 mM lyso phosphatidylcholine micelles

The linear nonapeptide hormone bradykinin (Arg¹‐Pro²‐Pro³‐Gly⁴‐Phe⁵‐Ser⁶‐Pro⁷‐Phe⁸‐Arg⁹) is involved, either directly or indirectly, in a wide variety of physiological processes, particularly pain and hyperanalgesia. Additional evidence suggests that bradykinin also plays a major role in inflammatory response, asthma, sepsis, and symptoms associated with the rhinoviral infection. It has long been speculated that a β‐turn at the C‐terminus of bradykinin plays a major role in the biological activity of the neuropeptide. The β‐turn forming potential of bradykinin in three vastly different local chemical environments, DMSO, 9 : 1 dioxane/water, and in the presence of 7.4 mM lyso phosphatidylcholine micelles, was investigated using two‐dimensional homonuclear nmr experiments coupled with simulated annealing calculations. The results of these investigations show that in all three systems residues 6–9 of the C‐terminus adopt very similar β‐turn like structures. These results suggest that the β‐turn at the C‐terminus of bradykinin is an important secondary structural feature for receptor recognition and binding. © 1994 John Wiley & Sons, Inc.