Determination of the backbone torsion psi angle by tensor correlation of chemical shift anisotropy and heteronuclear dipole–dipole interaction

We demonstrate that the backbone torsion psi angle of a uniformly labeled residue can be determined accurately by correlating the chemical shift anisotropy of the carbonyl carbon and the 13C– 1H heteronuclear dipole–dipole interaction of the alpha carbon. To obtain the highest sensitivity for the ps...

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Bibliographic Details
Published in:Solid state nuclear magnetic resonance 2007-04, Vol.31 (2), p.72-81
Main Authors: Mou, Yun, Tsai, Tim W.T., Chan, Jerry C.C.
Format: Article
Language:English
Subjects:
Alanine - chemistry
Anisotropy
Carbon Isotopes
CSA
Gamma-encoded
MAS
Nitrogen Isotopes
Nuclear Magnetic Resonance, Biomolecular - methods
RACO
Valine - chemistry
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Summary:We demonstrate that the backbone torsion psi angle of a uniformly labeled residue can be determined accurately by correlating the chemical shift anisotropy of the carbonyl carbon and the 13C– 1H heteronuclear dipole–dipole interaction of the alpha carbon. To obtain the highest sensitivity for the psi angle determination, the following conditions are desired: (i) the recoupling pulse sequences for the CSA and the heteronuclear dipolar interactions are gamma encoded, in which the spatial parts of m=2 are selected; (ii) the homonuclear polarization transfer is based on the scalar spin–spin coupling. Experimental data were obtained for [U– 13C, 15N]-alanine and N-acetyl-[U– 13C, 15N]- d, l-valine under magic-angle spinning at 25 kHz. Only three data points are required for the measurements and the dihedral angles determined are in excellent agreement with the diffraction data.
ISSN:0926-2040
1527-3326
DOI:10.1016/j.ssnmr.2007.01.003