The high-resolution crystal structure of a parallel-stranded guanine tetraplex

Science. 1994 Jul 22;265(5171):520-4. doi: 10.1126/science.8036494.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Computer Graphics
  • Crystallization
  • Crystallography, X-Ray
  • Guanine / chemistry*
  • Hydrogen Bonding
  • Molecular Structure
  • Nucleic Acid Conformation*
  • Oligodeoxyribonucleotides / chemistry*
  • Sodium


  • Oligodeoxyribonucleotides
  • Guanine
  • Sodium