title: Control of peptide helix sense by temperature tuning of noncovalent chiral domino effect.
abstract: We have investigated temperature effect on control of a peptide helix sense through the noncovalent chiral domino effect (NCDE: Inai, Y. et al., J. Am. Chem. Soc. 2003, 125, 8151-8162). Nonapeptide (1: Inai, Y.; Komori, H. Biomacromolecules 2004, 5, 1231-1240), which alone prefers a right-handed helix, maintained a screw-sense balance or a small imbalance at room temperature in the presence of Boc-d-amino acid. Cooling of the solution induced a left-handed helix more clearly. Conversely, heating from room temperature recovered the original right-handed sense. This helix-helix transition was essentially reversible in cooling-heating cycles. An increase in the Boc-d-amino acid concentration elevated temperature for switching CD signs based on the conformational transition. A similar thermal-driven inversion of helix sense was observed for 1 at other initial concentrations, suggesting that this behavior is insensitive to some peptide aggregation. NMR study provided direct evidence for the domino-type control of helix sense, in which Boc-Leu-OH is mainly located at the N-terminal segment. In addition, a left-handed helix induced by the d-isomer was shown to participate in equilibrium with a right-handed helix, whereas the right-handed helix was predominant in the presence of l-isomer. Consequently, we here have proposed a model for controlling a peptide helix sense (or its screw-sense bias) through temperature tuning of the external chiral interaction specific to the N-terminal sequence.
authors.affiliation: Department of Environmental Technology and Urban Planning, Shikumi College, Graduate School of Engineering, Nagoya Institute of Technology, Gokiso-cho, Showa-ku, Nagoya 466-8555, Japan.
authors.forename: Hisatoshi
authors.initials: H
authors.lastname: Komori
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Inai
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D002942:Circular Dichroism; D006860:Hydrogen Bonding; D007700:Kinetics; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D009842:Oligopeptides / Q000737:chemistry*; D011487:Protein Conformation; D013237:Stereoisomerism; D013696:Temperature; D013816:Thermodynamics
chemical_list: D000596:Amino Acids; D009842:Oligopeptides