Liquid-crystalline phases of circular superhelical plasmid DNA and their modification by the action of nuclease enzymes

Abstract

CD spectra of liquid-crystalline dispersions, X-ray diffraction patterns and optical textures of liquid crystals prepared from native superhelical DNA in poly(ethyleneglycol)-containing water–salt solutions before and after treatment of DNA with micrococcal nuclease have been obtained. It was found that condensation of native superhelical DNA is accompanied by the formation of liquid crystals with a non-specific optical texture. After treatment of the DNA, liquid-crystalline dispersions, with Micrococcal nuclease the DNA is able to form two similar types of liquid crystals with abnormal optical activity which differ in the peculiarities of their textures. The data obtained demonstrate the formation of multiple types of liquid crystals from high molar mass double-stranded optically active DNA molecules.