title: (S)-C alpha-ethyl, C alpha-benzylglycine [(S)-(alpha Et)Phe] peptides fold in left-handed helical structures.
abstract: The first x-ray diffraction structure analysis of a C alpha-ethyl, C alpha-benzylglycine [(alpha Et)Phe]-containing peptide, N alpha-benzyloxycarbonyl-alpha-aminoisobutyryl-alpha-amino-isobutyr yl-(S)- C alpha-benzylglycyl-alpha-aminoisobutyric acid (methanol solvate), has been performed. In the crystal state the N alpha-protected tetrapeptide is folded in an incipient, left-handed 3(10)-helical structure. This finding confirms that the relationship between (alpha Et)Phe alpha-carbon chirality and screw sense of the helix that is formed is opposite to that exhibited by protein amino acids, including Phe.
authors.affiliation: Osaka University of Pharmaceutical Sciences, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Doi
authors.forename: T
authors.initials: T
authors.lastname: Ishida
authors.forename: A
authors.initials: A
authors.lastname: Polese
authors.forename: F
authors.initials: F
authors.lastname: Formaggio
authors.forename: M
authors.initials: M
authors.lastname: Crisma
authors.forename: C
authors.initials: C
authors.lastname: Toniolo
authors.forename: Q B
authors.initials: QB
authors.lastname: Broxterman
authors.forename: J
authors.initials: J
authors.lastname: Kamphuis
mesh_terms: D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003460:Crystallization; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009842:Oligopeptides / Q000737:chemistry*; D017510:Protein Folding; D017433:Protein Structure, Secondary
chemical_list: D009842:Oligopeptides; C098300:benzyloxycarbonyl-aminoisobutyryl-aminoisobutyryl-(alpha-ethyl)phenylalanyl-aminoisobutyric acid