[Study of the interaction of proflavin with deoxytetraribonucleoside triphosphate 5'-d(ApGpCpT) in aqueous solution by uni- and two-dimensional 1H-spectroscopy].

Complex formation between acridine dye proflavine and self-complementary deoxytetraribonucleoside triphosphate 5'-d(ApGpCpT) in water-salt solution was studied by the method of one- and two-dimensional 1H-NMR spectroscopy (500 MHz). Two-dimensional homonuclear 1H-NMR spectroscopy (2D-COSY and 2D-NOESY) was used for complete assignments of proton signals of molecules in solution and for qualitative analysis of the nature of interactions between proflavine and tetranucleotide. Concentration dependences of proton chemical shifts of the molecules were measured at 293 K. Equilibrium reaction constants and limiting chemical shifts of dye protons in the complexes were determined using suggested schemes of complex formation. Based on the obtained data possible types of complexes were considered. Analysis of relative content of different types of complexes was made and special features of dynamic equilibrium were revealed as a function of correlation of dye and tetranucleotide concentrations. The most favourable structure of 1:2 complex of dye with tetranucleotide was constructed using the calculated values of induced chemical shifts of proflavine protons and 2D-NOESY spectra.