[Spectroscopic evidence of the interaction of the dye pyronine G with polynucleotides].

The interaction of pyronine G with mono- (AMP) and polynucleotides, i. e. poly(A) and poly(U), was studied at different pH values and temperatures, both in the visible and near UV ranges. It was found that pyronine G interacts only with purine type polynucleotides at neutral and alkaline pH. This was confirmed by the appearance of a new dye absorption band in the visible range and the existence of a hypochromic effect in the UV. The spectroscopical evidence for the formation of pyronine G--AMP or poly(U) complex has not been found at any conditions. With these results in view, possible binding mechanism of pyronine G to polynucleotides are discussed.