title: Refined crystal structure of an octanucleotide duplex with I.T. mismatched base pairs.
abstract: The structure of the synthetic deoxyoctamer d(GGIGCTCC) has been determined by single crystal X-ray diffraction techniques to a resolution of 1.7A. The sequence crystallises in space group P6(1), with unit cell dimensions a = b = 45.07, c = 45.49A. The refinement converged with a crystallographic residual R = 0.14 and the location of 81 solvent molecules. The octamer forms an A-DNA duplex with 6 Watson-Crick (G.C) base pairs and 2 inosine-thymine (I.T) pairs. Refinement of the structure shows it to be essentially isomorphous with that reported for d(GGGGCTCC) with the mispairs adopting a "wobble" conformation. Conformational parameters and base stacking interactions are compared to those for the native duplex d(GGGGCCCC) and other similar sequences. A rationale for the apparent increased crystal packing efficiency and lattice stability of the I.T octamer is given.
authors.affiliation: University Chemical Laboratory, Cambridge, UK.
authors.forename: W B
authors.initials: WB
authors.lastname: Cruse
authors.forename: J
authors.initials: J
authors.lastname: Aymani
authors.forename: O
authors.initials: O
authors.lastname: Kennard
authors.forename: T
authors.initials: T
authors.lastname: Brown
authors.forename: A G
authors.initials: AG
authors.lastname: Jack
authors.forename: G A
authors.initials: GA
authors.lastname: Leonard
mesh_terms: D001482:Base Composition; D007288:Inosine; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides; D013941:Thymine; D014961:X-Ray Diffraction
chemical_list: D009838:Oligodeoxyribonucleotides; D007288:Inosine; D013941:Thymine