title: Sequence-dependent conformational variations in the B-DNA double-helix of poly d(AATT).poly d(AATT).
abstract: X-ray diffraction data from well oriented and polycrystalline fibers of the lithium salt of poly d(AATT).poly d(AATT) are isomorphous with those from B-DNA. The double-helix consists of conformationally identical antiparallel strands and the molecular symmetry is 2 5(2); the asymmetric unit is a tetranucleotide, AATT, and 5 tetranucleotides span two turns per strand. Two double helices pass through a monoclinic unit cell of dimensions a = 31.05, b = 22.62, c = 33.85 A (fiber axis) and gamma = 90 degrees. In each repeating motif, the four nucleotides have distinct conformations, TpA displays an axial P-O bond and there is shortening of minor groove in the central region.
authors.affiliation: Whistler Center for Carbohydrate Research, Purdue University, West Lafayette, Indiana 47907.
authors.forename: R
authors.initials: R
authors.lastname: Chandrasekaran
authors.forename: A
authors.initials: A
authors.lastname: Radha
authors.forename: R L
authors.initials: RL
authors.lastname: Ratliff
mesh_terms: D001483:Base Sequence; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry*; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011089:Polydeoxyribonucleotides / Q000737:chemistry*
chemical_list: D011089:Polydeoxyribonucleotides; D004247:DNA; D004259:DNA-Directed DNA Polymerase