Conformational diversity of bradykinin in aqueous solution

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Abstract
The 600 MHz PMR spectra of bradykinin, [2-dehydroproline]bradykinin, [7-dehydroproline]bradykinin, and [5-tyrosine]bradykinin in aqueous solution were recorded and completely assigned by means of pH variation, spin-spin decoupling and chemical shift correlations. Analysis of the spin-spin coupling constants in the main chain and in the side chains suggests that bradykinin is in rapid equilibrium among many conformers and does not show any persistent structural features such as .beta. turns or internal hydrogen bonds. Addition of lipids or lipid-like materials [such as sodium (trimethylsilyl)propionate] in high concentration causes changes in the spectra, indicating specific interactions with Pro-7 and Phe-8, and a change in side-chain rotameric preference.