title: Unusual beta-sheet periodicity in small cyclic peptides.
abstract: Cyclic peptide homologs of gramicidin S containing 6, 8, 10, 12, 14 and 16 residues were synthesized and characterized using circular dichroism (CD) and 1H NMR spectroscopy. Based on the three-dimensional structures generated from these data we have found strong evidence of a periodic sequence-length dependence on beta-sheet content. In particular, peptides of length 6, 10 and 14 residues exhibit a high beta-sheet content, while peptides of 8, 12 and 16 residues appear to exist as random coils. This unusual beta-sheet periodicity may have important implications in our understanding of beta-sheet formation and in the design of constrained beta-sheet and beta-hairpin mimics.
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, Canada.
authors.forename: A C
authors.initials: AC
authors.lastname: Gibbs
authors.forename: L H
authors.initials: LH
authors.lastname: Kondejewski
authors.forename: W
authors.initials: W
authors.lastname: Gronwald
authors.forename: A M
authors.initials: AM
authors.lastname: Nip
authors.forename: R S
authors.initials: RS
authors.lastname: Hodges
authors.forename: B D
authors.initials: BD
authors.lastname: Sykes
authors.forename: D S
authors.initials: DS
authors.lastname: Wishart
mesh_terms: D000595:Amino Acid Sequence; D003198:Computer Simulation; D006096:Gramicidin / Q000031:analogs & derivatives / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D010456:Peptides, Cyclic / Q000138:chemical synthesis / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship
chemical_list: D010456:Peptides, Cyclic; D006096:Gramicidin