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.