[Calculation of x-ray diffuse scattering curves for DNA A- and B-forms in solution]

To obtain strictest theoretical indicatrices of X-ray scattering as well as to determine the volume and surface of DNA A- and B-forms in solution a new "cube" method has been applied which has been developed earlier for description of scattering intensity and geometric characteristics of particles with a complex surface topography. A new approach to calculation of diffuse scattering intensity of strongly elongated particles in solution has been proposed. Hydration of DNA molecules has been shown to considerably affect their X-ray scattering indicatrices. It has been also shown that the known Langridge method satisfactorily describes the DNA scattering indicatrix in the large-angle region but cannot be applied to analysis of DNA scattering intensity in the small-angle and large-angle ranges of the scattering curve simultaneously.