title: Oligopeptides with equal amounts of L- and D-amino acids may prefer a helix screw sense.
abstract: We investigated the preferred conformations of two nonapeptides, Boc-(L-Leu-D-Leu-Aib)3-OMe (2) and its enantiomer Boc-(D-Leu-L-Leu-Aib)3-OMe (ent-2), four dodecapeptides, Boc-(L-Leu-D-Leu-Aib)4-OMe (3), Boc-(L-Leu-Aib-D-Leu)4-OMe (4), Boc-(Aib-L-Leu-D-Leu)4-OMe (5), and Boc-(L-Leu-Aib-D-Leu-Aib)3-OMe (6), and a decapeptide, Boc-L-Leu-(D-Leu-L-Leu-Aib)3-OMe (7), in solution and in the crystalline state. The nonapeptide 2 formed a right-handed (P) α-helix, and its enantiomer ent-2 formed a left-handed (M) α-helix. The dodecapeptides 3 and 5 were folded into (P) helices, and 4 formed an (M) helical structure. As for 6, roughly equivalent amounts of (P) and (M) helices were observed in solution, and two (M) α-helices were detected in the crystalline state. Furthermore, the decapeptide 7, which possesses four L-Leu residues and three D-Leu residues, was folded into an (M) α-helix.
authors.affiliation: Division of Organic Chemistry, National Institute of Health Sciences , Tokyo 158-8501, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Demizu
authors.forename: Hiroko
authors.initials: H
authors.lastname: Yamashita
authors.forename: Norikazu
authors.initials: N
authors.lastname: Yamazaki
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Sato
authors.forename: Mitsunobu
authors.initials: M
authors.lastname: Doi
authors.forename: Masakazu
authors.initials: M
authors.lastname: Tanaka
authors.forename: Masaaki
authors.initials: M
authors.lastname: Kurihara
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D008968:Molecular Conformation; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D009842:Oligopeptides