[Some physico-chemical properties of the compact chromosome of Ananbaena variabilis].

It was shown that total DNA of the blue-green algae A. variabilis can be isolated as a compact particle with the sedimentation constant of 2700--2900S by lysis of the cells with the TritonX-100--sodium deoxycholate mixture in 1.0 M NaCl. The structure isolated is sensitive to ribonuclease and the hydrodynamic shift. It was found that within a compact chromosome A. variabilis DNA is circular and negatively superhelicized. The density of superturns of the DNA in 0,2 M NaCl at 20 degrees C is 0,061, which corresponds to one negative turn per 165 pairs of DNA bases.