title: A thyrotropin-releasing hormone analogue: pGlu-Phe-D-Pro-psi [CN4]-NMe at 293 and 107 K.
abstract: Data have been measured at two temperatures, 293 K and 107 K, for a crystal of a thyrotropin-releasing hormone analogue, pGlu-Phe-D-Pro-psi [CN4]-NMe, C20H25N7O3, and the structures solved and refined. The tripeptide contains a tetrazole ring which mimics a cis-peptide bond at the C terminus. An intermolecular hydrogen bond exists between two molecules related by the twofold screw axis, resulting in infinite chains of hydrogen-bonded peptide molecules. Because of the folding and packing of the molecules, there are no intermolecular contacts of less than 4 A to the N atom of the phenylalanine residue.
authors.affiliation: Hospital for Sick Children, Toronto, Canada.
authors.forename: P L
authors.initials: PL
authors.lastname: Howell
authors.forename: W A
authors.initials: WA
authors.lastname: Pangborn
authors.forename: G R
authors.initials: GR
authors.lastname: Marshall
authors.forename: J
authors.initials: J
authors.lastname: Zabrocki
authors.forename: G D
authors.initials: GD
authors.lastname: Smith
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D013696:Temperature; D013973:Thyrotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D009842:Oligopeptides; C098264:pyroglutamyl-phenylalanyl-prolyl-N-methyl-psi(5-tetrazole); D013973:Thyrotropin-Releasing Hormone; D011761:Pyrrolidonecarboxylic Acid