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.
The high-resolution crystal structure of a parallel-stranded guanine tetraplex.,Laughlan G, Murchie AI, Norman DG, Moore MH, Moody PC, Lilley DM, Luisi B Science. 1994 Jul 22;265(5171):520-4. PMID:8036494
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑ Laughlan G, Murchie AI, Norman DG, Moore MH, Moody PC, Lilley DM, Luisi B. The high-resolution crystal structure of a parallel-stranded guanine tetraplex. Science. 1994 Jul 22;265(5171):520-4. PMID:8036494