title: [Influence of ionic strength on the thermodynamic rigidity of the native DNA molecule in aqueous and aqueous-organic solvents].
abstract: The analysis of experimental and theoretical data for the dependence of the thermodynamic rigidity of the native DNA molecule on the ionic strength of solution has been fulfilled. It has been shown that in aqueous-salt solutions of DNA the statistical segment length (A) of the DNA molecule remains constant over the range of intermediate ionic strengths (mu > 0.002) and considerably increases over the range of small mu < 0.002. On the basis of viscosimetry and flowbirefringence measurements of aqueous-organic solutions of native DNA it has been hypothesized that the macromolecule's thermodynamic rigidity does not depend on the dielectric properties of the medium. In this connection it has been concluded that nonshielded Coulomb interactions between the nearest phosphate groups exert a stronger influence on the thermodynamic rigidity of the macromolecule as compared with Debye--Hückel interactions. The consideration of the hydrodynamical and optical data for aqueous organic DNA solutions of difinite ionic strength shows that the value of [n]/[eta] for DNA and consequently the optical anisotropy of the macromolecule remains constant irrespective of the presence of nonelectrolyte. On this basis it has been concluded that no appreciable alteration of the microform anisotropy occurs in all the systems under consideration.
mesh_terms: D004247:DNA; D007700:Kinetics; D008433:Mathematics; D009690:Nucleic Acid Conformation; D009994:Osmolar Concentration; D012997:Solvents; D013816:Thermodynamics; D014867:Water
chemical_list: D012997:Solvents; D014867:Water; D004247:DNA
vernacular_title: Vliianie ionnoĭ sily na termodinamicheskuiu zhestost' molekuly nativnoĭ DNK v vodnykh i vodno-organicheskikh rastvoriteliakh.