title: Effect of the ΔPhe residue configuration on a didehydropeptides conformation: A combined CD and NMR study.
abstract: Conformations of two pairs of dehydropeptides with the opposite configuration of the ΔPhe residue, Boc-Gly-Δ(Z)Phe-Gly-Phe-OMe (Z-OMe), Boc-Gly-Δ(E)Phe-Gly-Phe-OMe (E-OMe), Boc-Gly-Δ(Z)Phe-Gly-Phe-p-NA (Z-p-NA), and Boc-Gly-Δ(E)Phe-Gly-Phe-p-NA (E-p-NA) were compared on the basis of CD and NMR studies in MeOH, trifluoroethanol (TFE), MeCN, chloroform, and dimethylsulfoxide (DMSO). The CD results were used as the additional input data for the NMR-based determination of the detailed solution conformations of the peptides. It was found that E-OMe is unordered and Z-OMe, Z-p-NA, and E-p-NA adopt the β-turn conformation. There are two overlapping β-turns in each of those peptides: type II and type III' in Z-OMe and Z-p-NA, and two type III in E-p-NA. The ordered structure-inducing properties of Δ(Z)Phe and Δ(E)Phe in the peptides studied depend on the C-terminal blocking group. In methyl esters, the Δ(Z)Phe residue is a strong inducer of ordered conformations whereas the Δ(E)Phe one has no such properties. In p-nitroanilides, both isomers of ΔPhe cause the peptides to adopt ordered structures to a similar extent.
authors.affiliation: Faculty of Chemistry, University of Wrocław, 50-383 Wrocław, Poland. mbl@wchuwr.pl
authors.forename: Marek
authors.initials: M
authors.lastname: Lisowski
authors.forename: Lukasz
authors.initials: L
authors.lastname: Jaremko
authors.forename: Mariusz
authors.initials: M
authors.lastname: Jaremko
authors.forename: Adam
authors.initials: A
authors.lastname: Mazur
authors.forename: Rafał
authors.initials: R
authors.lastname: Latajka
authors.forename: Maciej
authors.initials: M
authors.lastname: Makowski
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D009842:Oligopeptides / Q000737:chemistry*; D010649:Phenylalanine / Q000737:chemistry*; D011487:Protein Conformation; D012996:Solutions; D013053:Spectrophotometry; D013237:Stereoisomerism; D013696:Temperature
chemical_list: D009842:Oligopeptides; D012996:Solutions; D010649:Phenylalanine