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A Nonpeptidic Reverse Turn that Promotes Parallel Sheet Structure Stabilized by C[BOND]H⋅⋅⋅O Hydrogen Bonds in a Cyclopropane γ-Peptide


  • We acknowledge funding from the Royal Society (M.D.S.), Organon/EPSRC (C.R.J.), AstraZeneca (F.R.T.), the Pakistani HEC (M.K.N.Q.), EPSRC National Mass Spectrometry Centre, and an International Human Frontier Science Program Long Term Fellowship LT00798/2005 (S.T.D.H.). We would like to thank Dr. J. Davies for help with X-ray crystallography.


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A twist of fate: Parallel-turn linkers comprising an amino acid derived alcohol conjoined with an aromatic amide through a flexible linkage adopt reverse-turn conformations. Cyclopropane tetra- and hexapeptide analogues form a C[BOND]H⋅⋅⋅O hydrogen-bond-stabilized parallel-sheet conformation (see scheme). NMR studies confirm the presence of hydrogen bonds in these structures.