A Crystalline β-Hairpin Peptide Nucleated by a Type I′ Aib-D-Ala β-Turn: Evidence for Cross-Strand Aromatic Interactions

Abstract

More pronounced twisting and divergence of the strands is seen for peptides containing type I′ turn nucleated β-hairpins. Superposition of the structure of the synthetic octapeptide Boc-Leu-Phe-Val-Aib-D-Ala-Leu-Phe-Val-OMe (black) with that of a peptide with the same strand residues but a type II′ turn nucleated β-hairpin (gray) illustrates the flattened nature of the latter. Aib=aminoisobutyric, Boc=tert-butoxycarbonyl.