title: Characterization of beta-bend ribbon spiral forming peptides using electronic and vibrational CD.
abstract: Terminally blocked (L-Pro-Aib)n and Aib-(L-Pro-Aib)n sequential oligopeptides are known to form right-handed beta-bend ribbon spirals under a variety of experimental conditions. Here we describe the results of a complete CD and ir characterization of this subtype of 3(10)-helical structure. The electronic CD spectra were obtained in solvents of different polarity in the 260-180 nm region. The vibrational CD and Fourier transform ir (FTIR) spectra were measured in deuterochloroform solution in the amide I and amide II (1750-1500 cm-1) regions. The critical chain length for full development of the beta-bend ribbon spiral structure is found to be five to six residues. Spectral effects related to concentration-induced stabilization of the structures of the longer peptides were seen in the resolution-enhanced FTIR spectra. Comparison to previous studies of (Aib)n and (Pro)n oligomers indicate that the low frequency of the amide I mode is due to the interaction of secondary and tertiary amide bonds and not to a strong difference in conformation from a regular 3(10)-helix.
authors.affiliation: Department of Chemistry, University of Illinois at Chicago 60607-7061.
authors.forename: G
authors.initials: G
authors.lastname: Yoder
authors.forename: T A
authors.initials: TA
authors.lastname: Keiderling
authors.forename: F
authors.initials: F
authors.lastname: Formaggio
authors.forename: M
authors.initials: M
authors.lastname: Crisma
authors.forename: C
authors.initials: C
authors.lastname: Toniolo
mesh_terms: D000595:Amino Acid Sequence; D000621:Aminoisobutyric Acids; D002942:Circular Dichroism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D017433:Protein Structure, Secondary; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000621:Aminoisobutyric Acids; D009842:Oligopeptides