title: Trishomocubane amino acid as a beta-turn scaffold.
abstract: The synthesis and X-ray structure of two diasteriomeric heptapeptides [Ac-Ala-Ala-Ala-(R/S)-Cage-Ala-Ala-Ala-NH2] with a trishomocubane amino acid as a beta-turn scaffold are reported. The amino acid was synthesized as a racemate and two diastereomeric peptides were obtained. The two peptides were separated by preparative high-pressure liquid chromatography and crystals suitable for X-ray analysis were grown for both diasteriomeric peptides. In general, both the peptides satisfy the criteria for beta-turn conformations. Five of the six Ala residues of both cage peptide crystals satisfy the criteria for 3(10)-helix characteristics and the cage amino acid residue satisfied the alpha-helix classification. These experimental results confirm previous theoretical studies in our laboratory which predicted that the cage moiety would be a strong/active beta-turn inducer.
authors.affiliation: Department of Organic Chemistry, University of Barcelona, Barcelona 08028, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Albericio
authors.forename: Per I
authors.initials: PI
authors.lastname: Arvidson
authors.forename: Krishna
authors.initials: K
authors.lastname: Bisetty
authors.forename: Ernest
authors.initials: E
authors.lastname: Giralt
authors.forename: Thavendran
authors.initials: T
authors.lastname: Govender
authors.forename: Samuel
authors.initials: S
authors.lastname: Jali
authors.forename: Palangpon
authors.initials: P
authors.lastname: Kongsaeree
authors.forename: Hendrik G
authors.initials: HG
authors.lastname: Kruger
authors.forename: Samran
authors.initials: S
authors.lastname: Prabpai
mesh_terms: D000596:Amino Acids / Q000138:chemical synthesis* / Q000737:chemistry; D018360:Crystallography, X-Ray; D018716:Molecular Mimicry; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D009842:Oligopeptides