Study by electronic circular dichroism spectroscopy of the interaction between aminooxy analogues of biogenic polyamines and selected oligonucleotides

The CD spectra of solutions containing different concentrations of the three aminooxy analogues and a 15-mer oligonucleotide, containing either the GC or the AT sequence, at a fixed concentration 60 μM in phosphate, were recorded. Solutions at pH values 7.5 and 5.0 were studied in order to investigate the role of the molecular charge. The spectra demonstrated that the interaction of these oligonucleotides with the aminooxy analogues had a significant sequence-selectivity. Spectra of the oligonucleotides in the presence of AOSMP showed two isodicroic points, thus indicating the presence of different oligonucleotide conformations in solution. The CD spectra of AOEPUT and APAPA supported the non-equivalent role that the outer ammonium groups of spermidine, N1 and N8 positions, could have in the interaction of this biogenic polyamine with DNA.