TRANSFORMATION OF GENOMIC-SIZE DNA FROM ISOTROPIC INTO LIQUID-CRYSTALLINE STATE

Restructuring of spatial organization of genomic-size DNA under microc occal nuclease treatment was studied. It was shown that as a result of phase separation in water-salt PEG solutions, the protein- and RNA-fr ee DNA from human K-262 cells forms spherical particles of -5 mu m (DN A-nuclei). The high DNA concentration in DNA-nuclei allows formation o f the liquid-crystalline (LC) state of DNA molecules. However, this tr ansformation is prohibited for steric and kinetic reasons. Cleavage of the DNA molecule in the DNA-nucleus with micrococcal nuclease is acco mpanied by rearrangement of its spatial organization to the cholesteri c liquid crystal. Such structural transformation may either occur with in one DNA-nucleus particle or expand to a number of neighboring parti cles. The transition was described in the framework of the Kolmogorov- Avramy equation.