title: Methanol-mediated, modular self-assembly of antiparallel beta-dimers. Crystal structure of C alpha backbone-modified tripeptide Bz-Aib-NHCOCO-Aib-OMe.
abstract: The backbone-modified tripeptide Bz-Aib-NHCOCO-Aib-OMe, in which the central C alpha has been replaced with CO, self-assembles in the solid state into highly ordered two-dimensional arrays through MeOH mediated intermolecular stacking of dimeric 'disk' modules formed by an antiparallel beta-sheet-type arrangement of tripeptide molecules. The C alpha(C'O)N(C'O)(C')NC alpha segment is nearly coplanar (average deviation from a mean least-square plane is +/- 0.037 A). The oxalyl moiety forms two pseudo-C5 intramolecular hydrogen bonds. Crystal parameters are as follows: C18H23N3)6.CH3OH, triclinic space group P1-, alpha = 9.796(4), b = 10.348(3), c = 11.836(4) A, alpha = 78.28(3), beta = 73.72(3), gamma = 69.45(3), R = 0.082 for 1747 reflections measured with [formula: see text].
authors.affiliation: Laboratory of the Structure of Matter, Naval Research Laboratory, Washington, DC, USA.
authors.forename: I K
authors.initials: IK
authors.lastname: Karle
authors.forename: D
authors.initials: D
authors.lastname: Ranganathan
mesh_terms: D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D000432:Methanol / Q000494:pharmacology*; D009842:Oligopeptides / Q000737:chemistry*; D011487:Protein Conformation
chemical_list: D009842:Oligopeptides; D000432:Methanol