title: Sequence effects of single base loops in intramolecular quadruplex DNA.
abstract: We have examined the properties of intramolecular G-quadruplexes in which the G3 tracts are separated by single base loops. The most stable complex contained 1',2'-dideoxyribose in all three loops, while loops containing T and C were slightly less stable (by about 2 degrees C). Quadruplexes containing loops with single A residues were less stable by 8 degrees C for each T to A substitution. These folded sequences display similar CD spectra, which are consistent with the formation of parallel stranded complexes with double-chain reversal loops. These results demonstrate that loop sequence, and not just length, affects quadruplex stability.
authors.affiliation: School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton SO16 7PX, UK.
authors.forename: Phillip A
authors.initials: PA
authors.lastname: Rachwal
authors.forename: Tom
authors.initials: T
authors.lastname: Brown
authors.forename: Keith R
authors.initials: KR
authors.lastname: Fox
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000737:chemistry* / Q000235:genetics*; D003855:Deoxyribose / Q000032:analysis; D054856:G-Quadruplexes; D009690:Nucleic Acid Conformation; D009841:Oligonucleotides / Q000737:chemistry / Q000235:genetics; D013816:Thermodynamics
chemical_list: D009841:Oligonucleotides; D003855:Deoxyribose; D004247:DNA