Conformational properties of DNA have been studied by scanning probe microscopy and the advantages of this method have been shown for the study of biopolymer morphology. It has been shown that in aqueous-alcohol solutions the linear DNA has the toroid-like conformation without any compacting agents. The conformational transition of the supercoiled DNA into the unfolded circle occurs under the cyclic DNA-surfactant interaction. Morphology of linear DNA in the complex with a surfactant has been determined. It has been assumed that the toroid-like conformation of linear DNA is energetically favorable when the DNA charge is neutralized.

SURFACE INVESTIGATION. X-ray, synchrotron and neutron techniques (1998), v. 14, pp. 247-251.