title: Conformational investigation of alpha, beta-dehydropeptides. Part VI. Molecular and crystal structure of benzyloxycarbonylglycyl-(Z)-dehydrophenylalanine.
abstract: The structure of a peptide containing C-terminal dehydrophenylalanine, Z-Gly-(Z)-delta Phe (C19H18N2O5, MW = 354) was determined from single-crystal X-ray diffraction data. Needle-shaped crystals were grown from a 1:1 mixture of methanol-acetone in the monoclinic space group P2(1) with a = 14.717(4), b = 4.941(2), c = 12.073(4) A, beta = 103.72(4) degrees; V = 852.86(8) A3, Z = 2 and Dc = 1.32 g cm-3. The structure was solved by direct methods using SHELXS-86 and refined to a final R-index of 0.032 for 1714 observed reflections. The peptide adopts a conformation folded at the glycine residue, and principal torsion angles are omega 0 = -167.6(2) degrees, phi 1 = -71.8(3) degrees, psi 1 = -31.6(4) degrees, omega 1 = -165.7(3) degrees, phi 2 = 65.6(4) degrees, psi 1(2) = -174.4(3) degrees and psi 2(2) = 5.2(4) degrees. Two intermolecular hydrogen bonds, N1-H...O0' and O2-H...O1', join the folded molecules into columns and link columns to each other, respectively. FTIR spectroscopy shows the presence of three hydrogen bonds. This third one has been interpreted as an intramolecular hydrogen bond of the N2-H...N1 type.
authors.affiliation: Department of Organic Chemistry, Pedagogical University of Opole, Poland.
authors.forename: B
authors.initials: B
authors.lastname: Rzeszotarska
authors.forename: J
authors.initials: J
authors.lastname: Karolak-Wojciechowska
authors.forename: M A
authors.initials: MA
authors.lastname: Broda
authors.forename: Z
authors.initials: Z
authors.lastname: Gałdecki
authors.forename: B
authors.initials: B
authors.lastname: Trzeźwińska
authors.forename: A E
authors.initials: AE
authors.lastname: Kozioł
mesh_terms: D004151:Dipeptides / Q000737:chemistry*; D011487:Protein Conformation; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D004151:Dipeptides; C092372:benzyloxycarbonyl-glycyl-dehydrophenylalanine; C092371:benzyloxycarbonyl-phenylalanyl-dehydrophenylalanine