Biopolym. Cell. 1989; 5(3):39-43.
Structure and Function of Biopolymers
Effect of the ionic solution strength on energy of DNA supercoiling
1Shurdov M. A., 1Gruzdev A. D.
  1. Institute of Cytology and Genetics, Siberian Branch of the Academy of Sciences of the USSR
    Novosibirsk, USSR


Binding isoterms of EtBr to supercoiled and relaxed pBR322 DNA were used to deter¬mine dependence of the free energy of DNA supercoiling g~Ka2 on NaCl concentration in the solution. It is shown that a decrease of concentration from 0.3 M to 0.01 M NaCl makes the value of K constant more than doubled and promote a significant reduction of the superhelical density — a. The free energy of DNA supercoiling decreases approximately by 20 per cent.


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