H-1-NMR STUDY OF THE STATES OF PALINDROMIC SEQUENCE 5'-D(GPCPGPAPAPGPC) IN AQUEOUS-SOLUTION

Equilibrium between various forms of a palindromic deoxyoligonucleotid e sequence 5'-d(GpCpGpApApGpC) in water-salt solution was studied by o ne-dimensional (500 MHz) and two-dimensional (600 MHz) H-1 NMR spectro scopy. Signals of heptadeoxynucleotide protons were completely assigne d by two-dimensional homonuclear H-1 NMR spectroscopy (2D TOCSY and 2D NOESY). The concentration (at 298 and 308 K) and temperature dependen ces of the chemical shifts of heptamer protons were found. The experim ental results were analyzed within a model of dynamic equilibrium betw een monomeric, hairpin, and dimeric forms of heptanucleotide in soluti on. The equilibrium constants, Delta H, and Delta S of hairpin and dim er formation were determined. Specific features of the concentration a nd temperature dependences of the portions of these forms were reveale d. The parameters obtained were compared with the literature data.