title: Conformational studies on peptides having dipropylglycine (Dpg) or 1-aminocycloheptanecarboxylic acid (Ac7c) within the sequence of l-leucine (Leu) residues.
abstract: A conformational analysis of peptides having dipropylglycine (Dpg) or 1-aminocycloheptanecarboxylic acid (Ac7c) within l-leucine (Leu) residues was conducted in solution and in a crystal state. Dpg and Ac7c had similar structures with acyclic and cyclic side chains, respectively. FTIR,1H NMR, and CD spectra measurements revealed that the preferred conformations of Dpg- and Ac7c-containing l-Leu peptides in solution were similar; both had a right-handed (P) 310-helix. The Dpg-containing octapeptide adopted a right-handed (P) α-helix in the crystal state. Dpg and Ac7c homopeptides had planar and helical structures as their preferred conformations, respectively; however, Dpg- and Ac7c-containing l-Leu peptides adopted similar structures in solution. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 210-218, 2016.
authors.affiliation: Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8521, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Oba
authors.affiliation: Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8521, Japan.
authors.forename: Hikaru
authors.initials: H
authors.lastname: Nonaka
authors.affiliation: Osaka University of Pharmaceutical Sciences, Osaka, 569-1094, Japan.
authors.forename: Mitsunobu
authors.initials: M
authors.lastname: Doi
authors.affiliation: Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, 852-8521, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Tanaka
keywords: conformation; helix; peptides; α,α-disubstituted α-amino acid