A 2H-NMR study of the DNA hydration water in solid Li-DNA assembles

High-resolution ²H-nmr is employed to monitor the D₂O in hydrated solids of Li-DNA prepared from solution by three different methods: lyophilization, slow evaporation of the water, and wet spinning in alcohol. From the spectral shapes and spin–spin relaxation measurements, the DNA in the lyophilized samples is found to be locally ordered with a domain size of ～ 0.4 μm. Much longer range macrosopic ordering is found in samples prepared by slow evaporation of the water. Here the DNA spontaneously assembles into a structure that is probably cholesteric, in which the pitch axis is perpendicular to the plane on which the DNA dried. The wet-spinning method produces macroscopically, uniaxially oriented DNA molecules with a maximum helix axis disorder of 12°. To aid in the comparison between calculated and experimental line shapes, a two-dimensional technique is employed to separate the contributions to the line width arising from DNA static disorder, magnetic inhomogeneities, and spin–spin relaxation.