β‐Turns induced in bradykinin by (S)‐α‐methylproline

Abstract
The ability or (S)‐α‐methylproline(α‐MePro) to stabilise reverse‐turn conformations in the peptide hormone bradykinin (BK = Arg1‐Pro2‐Pro3‐Gly4I‐Phe5‐Ser6‐Pro7‐Phe8‐Arg9) has been investigated. Two BK analogues containing α‐MePro at position 3 or position 7 were synthesised and their conformations in aqueous solution investigated by NMR spectroscopy. Whereas BK is largely disordered on the NMR time scale both analogues showed ROE connectivities in 2D‐ROESY spectra indicative of reverse‐turn conformations at both Pro2‐Phe5 and Ser6‐Arg9, whose formation appears to be cooperative. Some potential applications of α‐MePro as a reverse‐turn mimetic in the construction of synthetic peptide libraries is discussed.