title: Thermal stability and hydration state of DNA G-quadruplex regulated by loop regions.
abstract: We designed and synthesized DNA oligonucleotides that were able to fold into intramolecular DNA G-quadruplexes with different number of G-quartet planes and thymines in the each loop region [GmTn: m indicates the number of G-quartet planes (2 <or= m <or= 4), and n indicates the number of thymines in the each loop region (2 <or= n <or= 4)]. Effects of molecular crowding on structure of G-quadruplexes were investigated by circular dichroism spectra in buffers containing 0 wt% or 40 wt% PEG200 (poly(ethylene glycol) with an average molecular weight of 200). The results showed that G2T2, G2T3, G2T4 and G3T4 folded into antiparallel G-quadruplexes under the dilute and molecular crowding conditions. On the other hand, G3T2, G3T3, G4T2, G4T3, and G4T4 underwent structural transitions from antiparallel or mixture to parallel G-quadruplex by the addition of PEG200. These result and thermodynamic analysis of G2Tn demonstrated that loop regions had pivotal roles to determine structure and stability of G-qudruplexes.
authors.affiliation: Department of Chemistry, Faculty of Frontiers of Innovative Research in Science and Technology, Konan University, Kobe 650-0047, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Fujimoto
authors.forename: Daisuke
authors.initials: D
authors.lastname: Miyoshi
authors.forename: Hisae
authors.initials: H
authors.lastname: Tateishi-Karimata
authors.forename: Naoki
authors.initials: N
authors.lastname: Sugimoto
mesh_terms: D002942:Circular Dichroism; D004247:DNA / Q000737:chemistry*; D054856:G-Quadruplexes; D009691:Nucleic Acid Denaturation; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water; D004247:DNA