title: Spatial distribution of competing ions around DNA in solution.
abstract: The competition of monovalent and divalent cations for proximity to negatively charged DNA is of biological importance and can provide strong constraints for theoretical treatments of polyelectrolytes. Resonant x-ray scattering experiments have allowed us to monitor the number and distribution of each cation in a mixed ion cloud around DNA. These measurements provide experimental evidence to support a general theoretical prediction: the normalized distribution of each ion around polyelectrolytes remains constant when ions are mixed at different ratios. In addition, the amplitudes of the scattering signals throughout the competition provide a measurement of the surface concentration parameter that predicts the competition behavior of these cations. The data suggest that ion size needs to be taken into account in applying Poisson-Boltzmann treatments to polyelectrolytes such as DNA.
authors.affiliation: School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA.
authors.forename: K
authors.initials: K
authors.lastname: Andresen
authors.forename: R
authors.initials: R
authors.lastname: Das
authors.forename: H Y
authors.initials: HY
authors.lastname: Park
authors.forename: H
authors.initials: H
authors.lastname: Smith
authors.forename: L W
authors.initials: LW
authors.lastname: Kwok
authors.forename: J S
authors.initials: JS
authors.lastname: Lamb
authors.forename: E J
authors.initials: EJ
authors.lastname: Kirkland
authors.forename: D
authors.initials: D
authors.lastname: Herschlag
authors.forename: K D
authors.initials: KD
authors.lastname: Finkelstein
authors.forename: L
authors.initials: L
authors.lastname: Pollack
mesh_terms: D002412:Cations / Q000737:chemistry / Q000378:metabolism; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D008956:Models, Chemical; D009690:Nucleic Acid Conformation; D012413:Rubidium / Q000737:chemistry / Q000378:metabolism; D012542:Scattering, Radiation; D012996:Solutions; D013324:Strontium / Q000737:chemistry / Q000378:metabolism; D014965:X-Rays
chemical_list: D002412:Cations; D012996:Solutions; D004247:DNA; D012413:Rubidium; D013324:Strontium