Porphyrin induced Z to B conversion of poly(dG-dC)2 in ethanol

The water soluble porphyrins H2TMpyP-2, H2TMpyP-4, and CuTMpyP-4 are found to bind to Z-form poly(dG-dC)2 in 60% ethanol (v/v) and to facilitate the conversion of the polymer to the B form. Metalloporphyrins with axial ligands (MnTMpyP-4, ZnTMpyP-4) interact to some degree with the Z form, but do not lead to extensive conversion to the B form. The conversion of the Z form into the B form was determined by CD titration experiments, which were used to quantitate the fraction of poly(dG-dC)2 present in each conformation. Under all conditions each bound porphyrin molecule converts multiple base pairs from Z to B.