Double‐helical DNA and RNA circular dichroism. Calculations on base–sugar‐phosphate helix interactions

Theoretical calculations of the near ultraviolet (uv) circular dichroism of double‐helical DNA and RNA models were performed in order to evaluate the effects, on the calculated circular dichroism, of including the interactions of near uv quantum transitions of the nucleic acid bases with classical polarizable bonds of the sugar‐phosphate backbone. Double‐helical models (A‐form, B‐form, and C‐form DNA and RNA‐11) from X‐ray diffraction data were used in the calculations. The results indicate that the contributions to the circular dichroism in the near uv region, of these types of interactions, provide calculated spectra that are slightly altered from calculated spectra when only base–base transition interactions were considered.