Circular intensity differential scattering and chromatin-DNA structure. A combined theoretical approach.

Circular intensity differential scattering (CIDS) has been proven a powerful method in determining the higher-order structure of large biopolymers, such as chromatin. Theoretical predictions of the expected differential light scattering of circularly polarized light have previously been made for chromatin, either within the Born approximation, treating nucleosomes as noninteracting, oblate ellipsoids, or within a multiple dipole approximation, treating nucleosomes as interacting spheres. In order to conduct a meaningful interpretation of the CIDS signal in terms of given geometric parameters of the chiral structure, we have in this paper combined the two approaches considering the mutual interactions of ellipsoidal nucleosomes. In the process we have also found a confirmation for the validity of the Born approximation itself.