NMR study of daunomycin complexation with hexadeoxynucleotide 5 '-d(TPApCpGpTpA) in aqueous solution

Self-association of hexadeoxynucleotide 5'-d(TpApCpGpTpA) and its complexat ion with antitumor antibiotic daunomycin were studied by one- and two-dimen sional homonuclear H-1 NMR spectroscopy and heteronuclear H-1-P-31 NMR spec troscopy in water-salt solution. The concentration and temperature dependen ces of proton chemical shifts of the hexadeoxynucleotide and the ligand wer e measured, and equilibrium constants and thermodynamic parameters of corre sponding reactions were calculated on this basis using models for the forma tion of hexadeoxynucleotide duplex and its complex with the antibiotic. The spatial structure of daunomycin-d(TACGTA)(2) complex in solution was calcu lated using X-PLOR software on the basis of 2D NOE spectral data and the li mit values of proton chemical shifts of the ligand. Comparative analysis of different intermolecular interactions in sequence-specific binding of the antibiotic to the DNA fragment was carried out.