title: An extended planar C5 conformation and a 310-helical structure of peptide foldamer composed of diverse alpha-ethylated alpha,alpha-disubstituted alpha-amino acids.
abstract: Optically active peptide foldamers Tfa-[(S)-(alphaEt)Leu]-[(S)-(alphaEt)Nva]-Deg-[(S)-(alphaEt)Nle]-OEt (10) and Tfa-[(S)-(alphaEt)Val]-[(S)-(alphaEt)Leu]-[(S)-(alphaEt)Nva]-Deg-[(S)-(alphaEt)Nle]-OEt (11) composed of diverse alpha-ethylated alpha,alpha-disubstituted alpha-amino acids were synthesized. The dominant conformation of these peptides in solution was an unusual, fully extended planar conformation, and that in the crystal state was both right-handed (P) and left-handed (M) 3(10)-helical structures in 10 and a P 3(10)-helical structure in 11, respectively. The preferred planar C(5) conformation of the peptides prepared from chiral alpha-ethylated alpha,alpha-disubstituted alpha-amino acids was drastically different from the 3(10)-helical structure of the peptides prepared from chiral alpha-methylated alpha,alpha-disubstituted alpha-amino acids.
authors.affiliation: Graduate School of Pharmaceutical Sciences Kyushu University, Fukuoka 812-8582, Japan. mtanaka@phar.kyushu-u.ac.jp
authors.forename: Masakazu
authors.initials: M
authors.lastname: Tanaka
authors.forename: Shin
authors.initials: S
authors.lastname: Nishimura
authors.forename: Makoto
authors.initials: M
authors.lastname: Oba
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Demizu
authors.forename: Masaaki
authors.initials: M
authors.lastname: Kurihara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Suemune
mesh_terms: D000596:Amino Acids / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D010446:Peptide Fragments