title: Chiral interaction in peptide molecules: effects of chiral peptide species on helix-sense induction in an N-terminal-free achiral peptide.
abstract: Noncovalent chiral domino effect (NCDE) has been proposed as terminal-specific interaction upon a 3(10)-helical peptide chain, of which the helix sense is manipulated by an external chiral stimulus (mainly amino acid derivatives) operating on the N-terminus (Inai, Y., et al. J Am Chem Soc 2000, 122, 11731-11732; ibid., 2002, 124, 2466-2473; ibid., 2003, 125, 8151-8162). We have investigated here a helix-sense induction in an optically inactive N-terminal-free nonapeptide (1) through the screening of several peptide species that differ in chiral sequence, chain length, and C-terminal group. Helix-sense induction in peptide 1 depends largely on both the C-terminal chirality and carboxyl group in the external peptide, in which N-carbonyl-blocked amino acids, "monopeptide acids," should be the minimum requirement for effective induction. N-Protected mono- to tetrapeptides of L-Leu residue commonly induce a right-handed helix. NMR study and theoretical computation reveal that the N-terminal segment of peptide 1 binds the N-protected dipeptide molecule through multipoint coordination to induce a right-handed helix preferentially. The present findings not only will improve our understanding of the chiral roles in peptide or protein helical termini, but also might demonstrate potential applications to chirality-responsive materials based on peptide helical fragments.
authors.affiliation: Department of Environmental Technology and Urban Planning, Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan. inai@mse.nitech.ac.jp
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Inai
authors.forename: Naoki
authors.initials: N
authors.lastname: Ousaka
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ookouchi
mesh_terms: D000595:Amino Acid Sequence; D000621:Aminoisobutyric Acids / Q000737:chemistry; D002942:Circular Dichroism / Q000379:methods; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009842:Oligopeptides / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D013056:Spectrophotometry, Ultraviolet / Q000379:methods; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D000621:Aminoisobutyric Acids; D009842:Oligopeptides