[Nuclear magnetic resonance study of the conformation of nucleotides, oligonucleotides and their analogs. III. The sin-anti-equibrium in the solution of cytidine and 2'-deoxycytidine].

The method for determination of apparent rotation correlation time (tau c) on the basis of measurements of the spin-lattice relaxation rates of H(1') of the pyrimidine nucleosides and nucleotides both ribo- and deoxy-series after exchange of H(5) and H(6) on deuterium has been proposed. The recently suggested simple method of tau c calculation from H(5) relaxation rate was shown to lead to correct results. For cytidine and 2'-deoxycytidine the sin-anti-equilibrium constans in aqueous solutions were obtained. The anti-states were favorable in both cases. The long range coupling constant 5J1'5 corroborated the quantitative appreciation from the spin-lattice relaxation rates. The correction properties of the apparent rotation correlation time calculated by the proposed method are discussed.