title: Crystal structure at 1.5-A resolution of d(CGCICICG), an octanucleotide containing inosine, and its comparison with d(CGCG) and d(CGCGCG) structures.
abstract: The octadeoxyribonucleotide d(CGCICICG) has been crystallized in space group P(6)5(22) with unit cell dimensions of a = b = 31.0 A and c = 43.7 A, and X-ray diffraction data have been collected to 1.5-A resolution. Precession photographs and the self-Patterson function indicate that 12 base pairs of Z-conformation DNA stack along the c-axis, and the double helices pack in a hexagonal array similar to that seen in other crystals of Z-DNA. The structure has been solved by both Patterson deconvolution and molecular replacement methods and refined in space group P(6)5 to an R factor of 0.225 using 2503 unique reflections greater than 3.0 sigma (F). Comparison of the molecules within the hexagonal lattice with highly refined crystal structures of other Z-DNA reveals only minor conformational differences, most notably in the pucker of the deoxyribose of the purine residues. The DNA has multiple occupancy of C:I and C:G base pairs, and C:I base pairs adopt a conformation similar to that of C:G base pairs.
authors.affiliation: National Cancer Institute, Frederick Cancer Research and Development Center, Maryland 21702-1201.
authors.forename: V D
authors.initials: VD
authors.lastname: Kumar
authors.forename: R W
authors.initials: RW
authors.lastname: Harrison
authors.forename: L C
authors.initials: LC
authors.lastname: Andrews
authors.forename: I T
authors.initials: IT
authors.lastname: Weber
mesh_terms: D001482:Base Composition; D001483:Base Sequence; D003596:Cytosine / Q000737:chemistry; D004247:DNA / Q000737:chemistry*; D007288:Inosine / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D014961:X-Ray Diffraction
chemical_list: D009838:Oligodeoxyribonucleotides; D007288:Inosine; D003596:Cytosine; D004247:DNA