NMR Study of Complexation of Aromatic Ligands with Heptadeoxynucleotide 5"-d(GCGAAGC) Forming Stable Hairpin Structure in Aqueous Solution.

Complex formation of hairpin-producing heptadeoxynucleotide 5"-d(GCGAAGC) with aromatic molecules: acridine dye proflavine and anthracycline antibiotic daunomycin was studied by one-dimensional ¹H NMR and two-dimensional correlation ¹H–¹H (2D-TOCSY, 2D-NOESY), ¹H–³¹P (2D-HMBC) NMR spectroscopy (500 and 600 MHz) in aqueous solution. Concentration and temperature dependences for the chemical shifts of ligand protons were measured, molecular models of equilibrium in solution were developed, and equilibrium thermodynamic parameters for the formation of intercalation complexes were calculated. Spatial structures of dye and antibiotic complexes with the heptamer hairpin were constructed on the basis of 2D-NOE data and the calculated values of limiting chemical shifts of ligand protons. [ABSTRACT FROM AUTHOR]