Premium
Interaction des Ions Métalliques avec le DNA. II. Adsorption préférentielle de l'Ion césium par les Acides nucléiques
Author(s) -
DopplerBernardi F.,
Daune M.
Publication year - 1969
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1969.360070505
Subject(s) - chemistry , solvation , ion , solvation shell , adsorption , polynucleotide , analytical chemistry (journal) , chromatography , organic chemistry , biochemistry
Preferential adsorption of cations occurs in the solvated shell surrounding polyanions, especially polynucleotides and nucleic acids. The solvation parameter Γ is determined from sedimentation coefficients which are considered as pienometric determinations of the specific volume of the sample. By comparing two identical concentrations (0.1 M ) of monovalent salts, NaCl and CsCl, and using the model of DNA described in the preceding paper, one can relate the ratio S C s / S N a to solvation parameters Γ C s , and Γ N a .On the other hand, Γ can be related to the difference of energy W , between cation and water, to be extracted from the solution and placed in the vicinity of the polyanion. One finds generally a preferential solvation of the polarizable caesium ion by means of London–van der Waals interactions with bases. With reasonable assumptions, an estimate of W can be made, and the predicted value of Γ can be compared to the experimental one. An average of six sites is found around each base in a single‐stranded polymer, but‐only one in the double‐stranded structure. The amount of secondary structure can thus be estimated from the simple measurement of the ratio of two sediment constants.