title: Novel disulfide-constrained pentapeptides as models for beta-VIa turns in proteins.
abstract: The conformational behavior of cyclic peptides of the amino acid sequence Cys-Phe/Ala-Pro-Ala-Cys has been investigated through the combined use of molecular simulation methods and NMR experiments to find models for beta-VIa turns of proteins. Both oxidized (cyclic) peptides and reduced (linear) forms were investigated. At least 95% of the cyclic peptides show a cis conformation of the Xaa-Pro bond in solution in DMSO or water, whereas all other peptide bonds are trans. Furthermore, we observed a hydrogen bond between the NH group of residue Ala4 and the C = O group of residue Cys1. Both properties are indicative of beta-VIa turns. After reduction of the disulfide bridge, the all-trans form of the peptide bonds predominates.
authors.affiliation: Humboldt University Berlin, Institute of Chemistry, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Weisshoff
authors.forename: K
authors.initials: K
authors.lastname: Frost
authors.forename: W
authors.initials: W
authors.lastname: Brandt
authors.forename: P
authors.initials: P
authors.lastname: Henklein
authors.forename: C
authors.initials: C
authors.lastname: Mügge
authors.forename: C
authors.initials: C
authors.lastname: Frömmel
mesh_terms: D001483:Base Sequence; D004220:Disulfides; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D004220:Disulfides; D010455:Peptides