title: Structure and conformation in solution of the parallel-stranded hybrid alpha-d(CGCAATTCGC).beta-d(GCGTTAAGCG) by high-resolution 2D NMR.
abstract: The unnatural duplex oligonucleotide alpha-d(CGCAATTCGC).beta-d(GCGTTAAGCG) was analyzed by high-resolution NMR methods. All of the exchangeable imino and nonexchangeable protons of the duplex were assigned. Detection of all 10 of the exchangeable imino protons confirms that a parallel, unsymmetrical duplex is formed. The thermal stability of the parallel duplex is similar to the analogous antiparallel beta-beta duplex. The right handedness of the helix is confirmed by inter-residue [H8/H6-H1'] and [H8/H6-H2"] NOEs to the 5'-neighbor in the beta-strand and [H8/H6-H1'] NOEs to the 3'-neighbor in the alpha-strand. Intra-residue and inter-residue distances between base protons and deoxyribose protons in both strands were determined using the isolated spin-pair approximation for NOESY cross peaks acquired with mixing times 50 ms or less. The NOE data are consistent with a B-form geometry adopted by the alpha/beta hybrid decamer.
authors.affiliation: Department of Chemistry, University of Alberta, Edmonton, Canada.
authors.forename: W H
authors.initials: WH
authors.lastname: Gmeiner
authors.forename: B
authors.initials: B
authors.lastname: Rayner
authors.forename: F
authors.initials: F
authors.lastname: Morvan
authors.forename: J L
authors.initials: JL
authors.lastname: Imbach
authors.forename: J W
authors.initials: JW
authors.lastname: Lown
mesh_terms: D001483:Base Sequence; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*
chemical_list: D009838:Oligodeoxyribonucleotides