Étude, par diffusion centrale des Rayons X, des polyelectrolytes rigides en solution. Cas des sels de Li, Na et Cs du DNA

摘要: The study of polyelectrolytes in solution by small-angle x-ray scattering techniques involves special problems, raised the presence several species: solvent, macroions, counterions, and possibly ions an additional electrolyte. A theoretical treatment this problem is developed, based upon geometric concepts; applies to globular rodlike particles for case experiments carried out on absolute scale. equation obtained parameters: mass radius gyration particles; per unit length axial partial specific volumes neutral macromolecular component counterions added electrolyte; solvation species; fraction osmotically free. used interpret a series performed with Li, Na, Cs salts DNA water containing variable amounts chlorides each cation. effects concentration are first eliminated extrapolating infinite dilution at different concentrations; then pure results electrolyte concentration. parameters still involved stage length, If chosen agreement other data literature, if free assumed be 0.30 three salts, as suggested workers, structure molecules turns same cations, agree Watson-Crick model. These confirmed liquid–crystalline gels, higher concentration, that lead direct determination rods. Moreover determined shown cations. excellent those techniques.