The CD of ligand–DNA systems. I. Poly(dG‐dC) B‐DNA

A systematic theoretical study of the CD of double‐stranded poly (dG‐dC) and its complexes with small molecules is presented. The intrinsic CD of the polymer and the induced CD of a transition belonging to a molecule bound to DNA are calculated using the matrix method. The calculations show considerable differences between pyrimidine–purine and purine–pyrimidine binding sites, and we find that the induced CD of a groove bound molecule is one order of magnitude stronger than that of an intercalated molecule. The results form a sound basis for interpreting the CD of ligand–DNA systems in terms of molecular geometry, interactions, and spectroscopy.