Investigation of the influence of intramolecular electrostatic interactions on the conformational equilibrium in pyrimidine nucleosides by the PMR method
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The influence of solvents on the PMR spectra of uridine and cytidine has been studied. Because of intramolecular electrostatic interactions (IEIs) between the 2-keto oxygen and the freely rotating 2-hydroxyl, the position of the conformational equilibrium in the pyrimidine nucleosides but not in purine and deoxy nucleosides, depends substantially on the dielectric constant of the solvent and the size of the partial negative charge on the 2-keto oxygen of the base. It has been shown that an increase in the IEI leads to an increase in the 3′-endo (N) population of the ribose ring and to an increased influence of the temperature on the state of the conformational equilibrium.
KeywordsNucleoside Uridine Cytidine Dielectric Constant Purine Nucleoside
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