title: Crystal and molecular structure of the depsipeptide ionophore hexadecaisoleucinomycin, cyclo-[(D-Ile-L-Lac-L-Ile-D-Hyi)4-] (C80H136N8O24).
abstract: The crystal structure of a synthetic depsipeptide ionophore hexadecaisoleucinomycin, cyclo [-(D-Ile-L-Lac-L-Ile-D-Hyi)4-] (C80H136N8O24), has been determined by single crystal x-ray diffraction techniques. The crystals are orthorhombic, space group P2(1)2(1)2(1), number of molecules per unit cell z = 4, and cell parameters a = 11,195, b = 17.853, c = 54.835 A. The values of the standard (R) and weighted (Rw) discrepancy factors after refinement are 0.122 and 0.135, respectively. The structure is characterized by an elongated bracelet form with a twofold axis of pseudosymmetry. It is stabilized by eight intramolecular 4----1 hydrogen bonds between the amide C = O and N - H groups. The ester carbonyls are directed toward the inside of the molecule, their oxygen atoms forming an ellipsoidal internal cavity. The side chains are located on the molecular periphery. The conformational states of hexadecaisoleucinomycin in solution are discussed in the light of the data obtained.
authors.affiliation: Shemyakin Institute of Bioorganic Chemistry, USSR Academy of Sciences, Moscow.
authors.forename: V Z
authors.initials: VZ
authors.lastname: Pletnev
authors.forename: V T
authors.initials: VT
authors.lastname: Ivanov
authors.forename: D A
authors.initials: DA
authors.lastname: Langs
authors.forename: P
authors.initials: P
authors.lastname: Strong
authors.forename: W L
authors.initials: WL
authors.lastname: Duax
mesh_terms: D000595:Amino Acid Sequence; D006860:Hydrogen Bonding; D007476:Ionophores / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000737:chemistry*; D011487:Protein Conformation; D014634:Valinomycin / Q000031:analogs & derivatives* / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D007476:Ionophores; D010456:Peptides, Cyclic; D014634:Valinomycin; C067976:hexadecaisoleucinomycin