title: The high resolution crystal structure of the DNA decamer d(AGGCATGCCT).
abstract: The crystal structure of the DNA decamer d(AGGCATGCCT) has been determined to a resolution of 1.3 A and R factor of 13.9%. The structure has a unique conformation with each of the decamer single strands forming base-pairing interactions with two symmetry-related strands. The central eight bases of the decamer form an A-DNA octamer duplex with one symmetry-related strand whilst the terminal 5'-A and T-3' bases are flipped out and away from the octamer helix axis to form base-pairing interactions with a second symmetry-related strand. These A.T base-pairs lie perpendicular to the crystallographic c axis and pack within the unit cell in conjunction with a symmetry-related A.T base-pair displaced by 3.4 A degrees along the c axis. A novel base triplet interaction of the type A*(G.C) is present in the structure with interaction from the major groove side of the terminal 5'-A base to the minor groove of the central A-DNA octamer. This structure reports the first example of cobalt hexammine binding to a right-handed DNA duplex. The crystallographic asymmetric unit contains two cobalt hexammine ligands with one site in the major groove coordinating via hydrogen bonds to the 5'-AGG bases, and the second site located between DNA molecules and interacting with the oxygen atoms of phosphate groups.
authors.affiliation: The CRC Biomolecular Structure Unit, The Institute of Cancer Research, Sutton Surrey, UK.
authors.forename: C M
authors.initials: CM
authors.lastname: Nunn
authors.forename: S
authors.initials: S
authors.lastname: Neidle
mesh_terms: D003035:Cobalt / Q000737:chemistry; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry*; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry
chemical_list: D009838:Oligodeoxyribonucleotides; C032300:hexaamminecobalt(II); D003035:Cobalt; D004247:DNA