Determination of the ¹⁵N and ¹³C chemical shift tensors of L-[¹³C]alanyl-L-[¹⁵N]alanine from the dipole-coupled powder patterns

The 13C and 15N chemical shift tensors of L-[1-13C]alanyl-L-[15N]alanine have been determined from the dipole-coupled powder patterns and verified with the decoupled spectra. The principal values of the 13C tensor are σ11 = -115.5, σ22 = -42.3, and σ33 = 33.5 ppm, and the polar angles relating the 13C-15N bond to the chemical shift tensor are β = 90° and α = -39.5°. Although the 13C powder pattern widths of AlaAla and AcGlyAlaNH2 differ by only 2%, the anisotropy and asymmetry parameters differ by 10 and 25%, respectively. The principal values for the 15N chemical shift tensor are σ11= 65.3, σ22 = 78.1, and σ33 = 215.5 ppm, and the orientation of the 13C-15N bond to the σ33 axis is 106°. AlaAla and AcGlyAlaNH2 show a striking difference in asymmetry parameters (0.06 vs. 0.16) and anisotropy (144 vs. 165). © 1987 American Chemical Society.

Duke Scholars

Author Terrence Gilbert Oas Biochemistry