Dynamics in synthetic oligonucleotides. A solid-state deuterium NMR study.

Solid-state 2H NMR spectroscopy was used to investigate dynamics in the [methyl-2H]thymidine-labeled oligonucleotide [d(CGCGAATTCGCG)]2. Quadrupole echo line shapes, spin-lattice relaxation, and quadrupolar echo decay rates were investigated as a function of hydration W (moles of water/moles of nucleotide) between 0 and approximately 30. The amplitude of the base motion, modeled as a fast four-site libration, or diffusion in a cone, increased slightly with higher levels of hydration. A slower component of motion about the helix axis appears at W approximately 10 and increases in rate and amplitude, leading to the intermediate rate line shape observed at W approximately 21.