title: Peptide design 3(10)-helical conformation of a linear pentapeptide containing two dehydrophenylalanines, Boc-Gly-delta ZPhe-Leu-delta ZPhe-Ala-NHCH3.
abstract: alpha,beta-Dehydroamino acids are expected to provide conformational constraint to the peptide backbone. A pentapeptide containing two dehydrophenylalanines (delta ZPhe) separated by one L-amino acid has been synthesized and its solid state conformation determined. The pentapeptide, Boc-Gly-delta ZPhe-Leu-delta ZPhe-Ala-NHCH3, crystallizes from aqueous methanol in the orthorhombic space group P2(1)2(1)2(1). There are four formula units, C35H46N6O7, in a unit cell of dimensions a = 10.155(3), b = 15.175(1), and c = 23.447(2) A, at room temperature. The structure was solved by direct methods program, SIR88, and refined to a final R = 0.038 based on 3049 reflections with I > 2 sigma (I). All the peptide links are trans and the backbone conformation of the pentapeptide can be described as a 3(10)-helix, with mean phi,psi values of -65.1 degrees and -22.8 degrees (the value is averaged over the first four residues). There are four intramolecular 4-->1 type hydrogen bonds characteristic of 3(10)-type helices. In the crystal, the helices are held together by intermolecular N-H...O = C head-to-tail and lateral hydrogen bonding between symmetry related molecules. This mode of packing is similar to the packing motifs observed so often in other oligopeptides that adopt a 3(10)-helical structure.
authors: Oral Biology Department, University at Buffalo, New York 14214.
authors: K K
authors: KK
authors: Bhandary
authors: V S
authors: VS
authors: Chauhan
mesh_terms: D000595:Amino Acid Sequence; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry*; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D014961:X-Ray Diffraction
chemical_list: D009842:Oligopeptides; C081085:(1,1-dimethylethoxy)carbonyl-glycyl-delta-phenylalanyl-leucyl-delta-phenylalanyl-N-methylalaninamide; D010649:Phenylalanine; C018632:phenyldehydroalanine