title: Exceptionally slow kinetics of the intramolecular quadruplex formed by the Oxytricha telomeric repeat.
abstract: We examined the stability and kinetics of folding of the Oxytricha telomeric repeat sequence (G4T4)4. Fluorescence melting experiments show that this intramolecular quadruplex, which is more stable in potassium- than sodium-containing buffers, shows considerable hysteresis between the melting and annealing profiles, even when heated at a rate of 0.05 degrees C min(-1). Quantitative analysis of this hysteresis, together with temperature-jump relaxation experiments show that the dissociation is exceptionally slow with a half-life of about 10 years at 37 degrees C in the presence of 50 mM K+. The association reaction has a half-life of a few seconds at 37 degrees C, but becomes slower at elevated temperatures consistent with the suggestion that association occurs by a nucleation-zipper mechanism.
authors.affiliation: School of Biological Sciences, University of Southampton, Bassett Crescent East, Southampton, UKSO16 7PX.
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Brown
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: D000818:Animals; D004247:DNA / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D054856:G-Quadruplexes; D007700:Kinetics; D009690:Nucleic Acid Conformation; D009691:Nucleic Acid Denaturation; D016813:Oxytricha / Q000235:genetics*; D013050:Spectrometry, Fluorescence; D016615:Telomere / Q000235:genetics*; D013696:Temperature; D013816:Thermodynamics
chemical_list: D004247:DNA