Biopolymers and cell. 1989. Volume 5. № 3. 39 - 43

M. A. Shurdov, A. D. Gruzdev

EFFECT OF THE IONIC SOLUTION STRENGTH ON ENERGY OF DNA SUPERCOILING

Summary

    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 approxima¬tely by 20 per cent.