Magnitudes and Orientations of the ¹⁵N Chemical Shift Tensor of [1-¹⁵N]-2′-Deoxyguanosine Determined on a Polycrystalline Sample by Two-Dimensional Solid-State NMR Spectroscopy

The magnitudes and orientations of the ¹⁵N chemical shift tensor of [1-¹⁵N]-2′-deoxyguanosine were determined from a polycrystalline sample using the two-dimensional PISEMA experiment. The magnitudes of the principal values of the ¹⁵N chemical shift tensor of the N1 nitrogen of [1-¹⁵N]-2′-deoxyguanosine were found to be σ₁₁ = 54 ppm, σ₂₂ = 148 ppm, and σ₃₃ = 201 ppm with respect to (¹⁵NH₄)₂SO₄ in aqueous solution. Comparisons of experimental and simulated two-dimensional powder pattern spectra show that σ_33N is approximately collinear with the N-H bond. The tensor orientation of σ_33N for N1 of [1-¹⁵N]-2′-deoxyguanosine is similar to the values obtained for the side chain residues of ¹⁵N_∈1-tryptophan and ¹⁵Nπ-histidine even though the magnitudes differ significantly.