title: Effect of one D-Leu residue on right-handed helical -L-Leu-Aib- peptides in the crystal state.
abstract: Four diastereomeric-Leu-Leu-Aib-Leu-Leu-Aib-peptides, Boc-D-Leu-L-Leu-Aib-L-Leu-L-Leu-Aib-OMe (1), Boc-L-Leu-D-Leu-Aib-L-Leu-L-Leu-Aib-OMe (2), Boc-L-Leu-L-Leu-Aib-D-Leu-L-Leu-Aib-OMe (3), and Boc-L-Leu-L-Leu-Aib-L-Leu-D-Leu-Aib-OMe (4), were synthesized. The crystals of the four hexapeptides were characterized by X-ray crystallographic analysis. Two diastereomeric hexapeptides 1 and 2 having D-Leu(1) or D-Leu(2) were folded into right-handed (P) 3(10)-helical structures, while peptide 3 having D-Leu(4) was folded into a turn structure nucleated by type III' and I' beta-turns, and peptide 4 having D-Leu(5) was folded into a left-handed (M) 3(10)-helical structure.
authors.affiliation: Division of Organic Chemistry, National Institute of Health Sciences, Setagaya, Tokyo, Japan. demizu@nihs.go.jp
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Demizu
authors.forename: Mitsunobu
authors.initials: M
authors.lastname: Doi
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Sato
authors.forename: Masakazu
authors.initials: M
authors.lastname: Tanaka
authors.forename: Haruhiro
authors.initials: H
authors.lastname: Okuda
authors.forename: Masaaki
authors.initials: M
authors.lastname: Kurihara
mesh_terms: D000595:Amino Acid Sequence; D003460:Crystallization; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D007930:Leucine / Q000737:chemistry*; D009842:Oligopeptides / Q000138:chemical synthesis / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013237:Stereoisomerism
chemical_list: D009842:Oligopeptides; D007930:Leucine