Document 0456
 DOCN  M9480456
 TI    The high-resolution crystal structure of a parallel-stranded guanine
       tetraplex.
 DT    9410
 AU    Laughlan G; Murchie AI; Norman DG; Moore MH; Moody PC; Lilley DM; Luisi
       B; Medical Research Council Virology Unit, University of Glasgow,; UK.
 SO    Science. 1994 Jul 22;265(5171):520-4. Unique Identifier : AIDSLINE
       MED/94310435
 AB    Repeat tracts of guanine bases found in DNA and RNA can form tetraplex
       structures in the presence of a variety of monovalent cations. Evidence
       suggests that guanine tetraplexes assume important functions within
       chromosomal telomeres, immunoglobulin switch regions, and the human
       immunodeficiency virus genome. The structure of a parallel-stranded
       tetraplex formed by the hexanucleotide d(TG4T) and stabilized by sodium
       cations was determined by x-ray crystallography to 1.2 angstroms
       resolution. Sharply resolved sodium cations were found between and
       within planes of hydrogen-bonded guanine quartets, and an ordered groove
       hydration was observed. Distinct intra- and intermolecular stacking
       arrangements were adopted by the guanine quartets. Thymine bases were
       exclusively involved in making extensive lattice contacts.
 DE    Computer Graphics  Crystallization  Crystallography, X-Ray
       Guanine/*CHEMISTRY  Hydrogen Bonding  Molecular Structure  *Nucleic Acid
       Conformation  Oligodeoxyribonucleotides/*CHEMISTRY  Sodium  Support,
       Non-U.S. Gov't  JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).