Effect of Single-Charged Anions of Different Nature on the DNA Molecule Conformation in Water-Salt Solutions

摘要

Methods of intrinsic viscosity (#eta#) and beam flow birefringence were used to study the effects of some single-charged ions (F~-, Cl~-, Br~-, I~-, NO_2~-, NO_3~-, ClO_4~-, SCN~-, CH_3COO~-) on the size and thermodynamic rigidity of a DNA molecule in aqueous solutions of sodium salts in a broad interva of ionic strength #mu# when temperature T is changed. It has been shown that the close interactions in a macromolecule and the resulting DNA persistent length a are independent of the type of the salt anion over the whole interval of #mu#. On the contrary, the specific volume of the DNA molecule in solution, proportional to the #etaA#value, is quite sensitive to the anionic composition of the solvent, which is due to the effect of anions and their hydration on the long-range interactions in the macromolecule. The presence of polyatomic and halide anions is manifested differently in the #eta# value of DNA. Possible factors responsible for the observed effect and the role of structural alterations of water upon aion hydration are discussed.