This study demonstrates the mutual orientation of three tensor interactions in a single NMR experiment. The orientation of the 15N chemical shift tensor relative to the molecular frame has thus been determined in polycrystalline L-[1-13C] alanyl-L-[15N] alanine. The 13C-15N and 15N-1H dipole interactions are determined using the 1H dipole-modulated, 13C dipole-coupled 15N spectrum obtained as a transform of the data in t2. From simulations of the experimental spectra, two sets of polar angles have been determined relating the 13C- 15N and 15N-1H dipoles to the 15N chemical shift tensor. The values determined are βCN = 106°, αCN = 5° and βNH = -19°, αNH = 12°. The experiment verifies, without reference to single crystal data, that σ33 lies in the peptide plane and σ22 is nearly perpendicular to the plane.
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Physical and Theoretical Chemistry