title: Salt dependence of the radius of gyration and flexibility of single-stranded DNA in solution probed by small-angle x-ray scattering.
abstract: Short single-stranded nucleic acids are ubiquitous in biological processes; understanding their physical properties provides insights to nucleic acid folding and dynamics. We used small-angle x-ray scattering to study 8-100 residue homopolymeric single-stranded DNAs in solution, without external forces or labeling probes. Poly-T's structural ensemble changes with increasing ionic strength in a manner consistent with a polyelectrolyte persistence length theory that accounts for molecular flexibility. For any number of residues, poly-A is consistently more elongated than poly-T, likely due to the tendency of A residues to form stronger base-stacking interactions than T residues.
authors.affiliation: Applied Physics Department, Stanford University, Stanford, California 94305, USA.
authors.forename: Adelene Y L
authors.initials: AY
authors.lastname: Sim
authors.forename: Jan
authors.initials: J
authors.lastname: Lipfert
authors.forename: Daniel
authors.initials: D
authors.lastname: Herschlag
authors.forename: Sebastian
authors.initials: S
authors.lastname: Doniach
mesh_terms: D004277:DNA, Single-Stranded / Q000737:chemistry*; D009690:Nucleic Acid Conformation / Q000187:drug effects*; D012399:Rotation; D012492:Salts / Q000494:pharmacology*; D053838:Scattering, Small Angle; D012996:Solutions; D014961:X-Ray Diffraction
chemical_list: D004277:DNA, Single-Stranded; D012492:Salts; D012996:Solutions