title: The human telomere sequence, (TTAGGG)4, in the absence and presence of cosolutes: a spectroscopic investigation.
abstract: Historically, biophysical studies of nucleic acids have been carried out under near ideal conditions, i.e., low buffer concentration (e.g., 10 mM phosphate), pH 7, low ionic strength (e.g., 100 mM) and, for optical studies, low concentrations of DNA (e.g., 1×10⁻⁶ M). Although valuable structural and thermodynamic data have come out of these studies, the conditions, for the most, part, are inadequate to simulate realistic cellular conditions. The increasing interest in studying biomolecules under more cellular-like conditions prompted us to investigate the effect of osmotic stress on the structural and thermodynamic properties of DNA oligomers containing the human telomere sequence (TTAGGG). Here, we report the characterization of (TTAGGG)4 in potassium phosphate buffer with increasing percent PEG (polyethylene glycol) or acetonitrile. In general, the presence of these cosolutes induces a conformational change from a unimolecular hybrid structure to a multimolecular parallel stranded structure. Hence, the structural change is accompanied with a change in the molecularity of quadruplex formation.
authors.affiliation: Department of Chemistry and Biochemistry, Texas Woman's University, Denton, TX 76204, USA. vsharma@twu.edu.
authors.forename: Vishal R
authors.initials: VR
authors.lastname: Sharma
authors.affiliation: Department of Chemistry and Biochemistry, Texas Woman's University, Denton, TX 76204, USA. rsheardy@twu.edu.
authors.forename: Richard D
authors.initials: RD
authors.lastname: Sheardy
mesh_terms: D001483:Base Sequence; D002942:Circular Dichroism; D054856:G-Quadruplexes / Q000187:drug effects; D006801:Humans; D009690:Nucleic Acid Conformation / Q000187:drug effects*; D009997:Osmotic Pressure; D010710:Phosphates / Q000494:pharmacology*; D011092:Polyethylene Glycols / Q000737:chemistry; D017680:Potassium Compounds / Q000494:pharmacology*; D016615:Telomere / Q000737:chemistry* / Q000187:drug effects* / Q000235:genetics; D013816:Thermodynamics
chemical_list: D010710:Phosphates; D017680:Potassium Compounds; D011092:Polyethylene Glycols; C013216:potassium phosphate