Sodium ion and solvent nuclear relaxation results in aqueous solutions of DNA

The field‐dependent23Na nuclear relaxation in aqueous DNA solutions has been obtained for a range of temperatures, including the DNA melting region. At least two correlation times are needed to characterize the spectral density function for the23Na relaxation. For the slow process (with the largest correlation time), the temperature dependence of the coupling constant and the correlation time were determined, and important premelting effects were observed. Possible origins of the slow process are discussed. The last process is shown to be correlated with the properties of the hydration water of DNA as reflected by the17O relaxation rates in these solutions. The influence of the polyelectrolyte and NaCl concentrations on the23Na relaxation rate is compared with previous results from solutions of linear flexible polyelectrolytes.