[Study of complex formation of ethidium bromide with the self-complementary deoxytetranucleotide 5'-d(ApGpCpT) by unidimensional and two- dimensional 1H NMR spectroscopy]. / Issledovanie kompleksoobrazovaniia bromistogo étidiia s samokomplementarnym dezoksitetranukleotidom 5'-d(ApGpCpT) metodom odnomernoi i dvumernoi 1H IaMR-spektroskopii.

Complex formation of ethidium bromide (3,8-diamino-6-phenyl-5-ethyl-phenanthridine) with the self-complementary desoxytetraribonucleosidetriphosphate d(ApGpCpT) was studied in aqueous solution by uni- and two-dimensional 1H NMR spectroscopy (500 and 600 MHz). The concentration dependence of the chemical shifts of protons of the complex at a fixed temperature (T = 308 K) were measured. The schemes of complexing of the dye with the tetranucleotide which take into account eventual molecular associates in solution are discussed. Equilibrium constants of the reactions and the limiting values for the chemical shifts of the protons of ethidium bromide incorporating into the complex were calculated. Relative contents of different complex types were analyzed. The relationship between the dynamic equilibrium and dye/tetranucleotide concentration ratio was examined. The conclusion is made that, as with the complex of proflavine with the d(AGCT) examined earlier, ethidium bromide is intercalated essentially into the G-C site of the tetranucleotide being in the duplex form. The difference in intercalation between ethidium bromide and proflavine lies in the fact that ethidium bromide incorporate on the side of the narrow groove, whereas proflavine is built in on the side of the large groove. Based on the calculated values of the induced chemical shift of ethidium bromide protons and 2-d NOE spectal data, an adequate model (1:2) of the complex of the dye with tetranucleotide in solution was constructed.

[Study of the self-association of deoxytetraribonucleoside triphosphate molecules d(ApGpCpT) in aqueous solution by one-dimensional and two- dimensional (1)H NMR spectroscopy]. / Issledovanie samoassotsiatsii molekul dezoksitetraribonukleozidtrifosfatov d(ApGpCpT) v vodnom rastvore metodom odnomernoi i dvumernoi (1)H IaMR-spektroskopii.

Equilibrium behaviour of self-complimentary deoxytetranucleotides d(ApGpCpT) in D2O solution has been studied by the method of proton magnetic resonance spectroscopy (500 MHz). Complete assignments of the d(ApGpCpT) protons were obtained from both two-dimensional homonuclear COSY- and NOESY-experiments. Concentration and temperature dependences of tetranucleotide proton chemical shifts have been investigated. The equilibrium association constants and thermodynamical parameters of self-association of the molecules have been calculated using theoretical models and regression equations based on experimental results.

[Study of the interaction of proflavin with deoxytetraribonucleoside triphosphate 5'-d(ApGpCpT) in aqueous solution by uni- and two-dimensional 1H-spectroscopy]. / Issledovanie vzaimodeistivia proflavina s dezoksitetraribonukleozidtrifosfatom 5'-d(ApGpCpT), v vodnom rastvore metodom odno- i dvumernoi 1H IaMR-spektroskopii.

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.