title: Osmotic properties of DNA: critical evaluation of counterion condensation theory.
abstract: The osmotic coefficient of B-DNA in water may, in dilute solutions, deviate by as much as 100% from predictions based on a simple line-charge "counterion condensation" theory. In contrast, a cell model description of the ionic atmosphere near a cylindrical polyelectrolyte predicts osmotic properties that are in surprisingly good harmony with all available experimental findings over a wide range of DNA concentrations. We argue that the neglect of molecular features, such as finite radius, makes line-charge condensation theory inapplicable at all but impractically low polyelectrolyte concentrations.
authors.affiliation: Laboratory of Physical and Structural Biology National Institute of Child Health and Human Development National Institutes of Health, Bethesda, Maryland 20892-5626, USA.
authors.forename: P L
authors.initials: PL
authors.lastname: Hansen
authors.forename: R
authors.initials: R
authors.lastname: Podgornik
authors.forename: V A
authors.initials: VA
authors.lastname: Parsegian
mesh_terms: D002477:Cells / Q000737:chemistry*; D003198:Computer Simulation; D004247:DNA / Q000737:chemistry*; D004058:Diffusion; D004563:Electrochemistry / Q000379:methods*; D004573:Electrolytes / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D008954:Models, Biological; D008956:Models, Chemical; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009995:Osmosis / Q000502:physiology*; D009997:Osmotic Pressure; D012996:Solutions; D055672:Static Electricity; D013499:Surface Properties
chemical_list: D004573:Electrolytes; D007477:Ions; D012996:Solutions; D004247:DNA