Fig. 5.

Amide chemical shift tensor analysis for protein GB1. (A) Principal elements of ¹⁵N tensor in the traceless representation compared to previously published slow-MAS data. Principal elements are presented in black with error bars corresponding to one standard deviation. Tensor values from previous work are presented in red. The rmsd between δ₁₁ elements from both datasets is 1.6 ppm, and 6 ppm for δ₂₂ and δ₃₃ values corresponding to a deviation of η of 0.13. (B) Chemical shift tensor elements plotted against isotropic chemical shift. The correlation reveals that the changes in the isotropic chemical shift result from largely correlated shifts of all three principal elements. R² for each element (δ₁₁, δ₂₂, δ₃₃) are 0.82, 0.75, and 0.62, respectively. (C) The angle β (a1) as a function of residue number. The angle β defines the orientation of the δ₁₁/δ_zz tensor element to the HN bond dipole.