Design of Peptide Models for β-Hairpins and Equilibrating Helix-Hairpin Structures

Abstract

It is well established that synthetic peptides containing a centrally positioned Type-I′ or Type-II′ β-turn can form well folded peptide hairpins. Earlier studies from this laboratory have established that D-Pro-Xxx segments nucleate β-hairpin structures, with formation of a central Type-II′ β-turn. The octapeptide (Boc-Leu-Phe-Val-Aib-D-AlaLeu-Phe- Val-OMe) is a rare example of a synthetic peptide hairpin, containing a central Type-I′ β-turn. Hairpins with Type-I′ turns are considerably more twisted than their Type-II′ counterparts. The Aib-Xxx segment has also been shown to adopt a Type-I β- turn structure, resulting in incorporation into the centre of a long synthetic, helical peptide.

Keywords: Helix, Hairpin, Secondary Structure, Peptides, Folding