Chiral interaction in Gly‐capped N‐terminal motif of 3₁₀‐helix and domino‐type induction in helix sense

Chiral interaction of helical peptide with chiral molecule, and concomitant induction in its helix sense have been demonstrated in optically inactive nonapeptide ( 1 ) possessing Gly at its N‐terminus: H–Gly–(Δ Z Phe–Aib) 4 –OCH 3 ( 1 : Δ Z Phe = Z‐dehydrophenylalanine; Aib = α‐aminoisobutyric acid). Spectroscopic measurements [mainly nuclear magnetic resonance (NMR) and circular diochroism (CD)] as well as theoretical simulation have been carried out for that purpose. Peptide 1 in the 3 10 ‐helix tends to adopt preferentially a right‐handed screw sense by chiral Boc‐ L ‐amino acid (Boc: t ‐butoxycarbonyl). Induction in the helix sense through the noncovalent chiral domino effect should be derived primarily from the complex supported by the three‐point coordination on the N‐terminal sequence. Thus the 3 10 ‐helical terminus consisting of only α‐amino acid residues enables chiral recognition of the Boc‐amino acid molecule, leading to modulation of the original chain asymmetry. Dynamics in the helix‐sense induction also have been discussed on the basis of a low‐temperature NMR study. Furthermore, the inversion of induced helix sense has been achieved through solvent effects. © 2006 Wiley Periodicals, Inc. Biopolymers 83:337–351, 2006 This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com