title: Packing features of the all-AT oligonucleotide d(AAATTT).
abstract: We describe the packing features of the oligonucleotide duplex d(AAATTT)2, as determined by X-ray diffraction. There is little information on sequences that only contain A and T bases. The present structure confirms that these sequences tend to pack as a helical arrangement of stacked oligonucleotides in a B conformation with Watson-Crick hydrogen bonding. Our results demonstrate that the virtual TA base step between stacked duplexes has a negative twist that improves base stacking. This observation is consistent with the low stability of TA base steps in B-form DNA.
authors.affiliation: Departament d'Enginyeria Quimica, Universitat Politecnica de Catalunya, Av. Diagonal 647, E-08028 Barcelona, Spain.
authors.forename: N
authors.initials: N
authors.lastname: Valls
authors.forename: A
authors.initials: A
authors.lastname: Santaolalla
authors.forename: J L
authors.initials: JL
authors.lastname: Campos
authors.forename: J A
authors.initials: JA
authors.lastname: Subirana
mesh_terms: D000225:Adenine; D001483:Base Sequence; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D013941:Thymine; D014961:X-Ray Diffraction
chemical_list: D009838:Oligodeoxyribonucleotides; D000225:Adenine; D013941:Thymine