Base pair selectivity in the binding of copper (II) tetrakis (4-N-methylpyridyl)porphine to polynucleotides under closely packed conditions.

The base pair selectivity of the intercalative binding of the copper porphyrin, copper (II) tetrakis(4-N-methylpyridyl)porphine (Cu(II)TMpyP-4), to DNA has been investigated using a variety of DNA types and the synthetic polynucleotides poly(dG-dC)2 and poly(dA-dT)2. The studies utilize electron paramagnetic resonance of concentrated gels which are thought to mimic the closely packed state of nuclear DNA. The results indicate that intercalation of this porphyrin is preferred for sites containing two adjacent G-C base pairs, irrespective of sequence.