title: The delineation of hydrogen-bonding patterns in supramolecular self-assembly of several core oxalo retro-peptides and crystal structure of MeO-Ser-Leu-COCO-Leu-Ser-OMe.
abstract: Pseudo-C5-type intramolecular hydrogen bonding, arising from the C2 disposition of the core NH-CO-CO-NH unit in oxalo retro-peptides, is formed in addition to extended hydrogen bonding with neighbors forming sheets in MeO-Aib-COCO-Aib-OMe (1), helices in MeO-Leu-COCO-Leu-OMe (2) and ribbons in MeO-Ser-Leu-COCO-Leu-Ser-OMe (3). In 3 the OH in the Ser side-chains form hydrogen bonds with the backbone carbonyl of Leu groups from neighboring molecules. Crystal parameters for 3 are: C22H38N4O10, monoclinic, space group P2(1), a = 7.374(1), b = 18.218(4), c = 10.661(3) A, beta = 95.72(2) degrees, R = 0.063 for 1738 observed reflections with [formula: see text].
authors.affiliation: Laboratory for the Structure of Matter, Naval Research Laboratory, Washington, DC, USA.
authors.forename: I L
authors.initials: IL
authors.lastname: Karle
authors.forename: D
authors.initials: D
authors.lastname: Ranganathan
mesh_terms: D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D009842:Oligopeptides / Q000737:chemistry*; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D013057:Spectrum Analysis
chemical_list: C096048:N,N'-oxalobis(leucylserine) dimethyl ester; D009842:Oligopeptides