title: Chiral interaction in Gly-capped N-terminal motif of 3(10)-helix and domino-type induction in helix sense.
abstract: 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-(Delta(Z)Phe-Aib)(4)-OCH(3) (1: Delta(Z)Phe = Z-dehydrophenylalanine; Aib = alpha-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 alpha-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.
authors.affiliation: Department of Environmental Technology and Urban Planning, Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Ousaka
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Inai
authors.forename: Takahiro
authors.initials: T
authors.lastname: Okabe
mesh_terms: D000621:Aminoisobutyric Acids / Q000737:chemistry; D002942:Circular Dichroism; D005998:Glycine / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D000621:Aminoisobutyric Acids; D010455:Peptides; D005998:Glycine