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AbstractAbstract
[en] A method is presented that makes it possible to estimate both the orientation and the magnitude of the chemical shift anisotropy (CSA) tensor in molecules with a pair of spin 1/2 nuclei, typically 13C-1H or 15 N-1H. The method relies on the fact that the longitudinal cross-correlation rate as well as a linear combination of the autorelaxation rates of longitudinal heterospin magnetization, longitudinal two-spin order and longitudinal proton magnetization are proportional to the spectral density at the Larmor frequency of the heterospin. Therefore the ratio between the cross-correlation rate and the above linear combination is independent of the dynamics. From the field dependence of the ratio both the magnitude and the orientation of the CSA tensor can be estimated. The method is applicable to molecules in all motional regimes and is not limited to molecules in extreme narrowing or slow tumbling, nor is it sensitive to chemical exchange broadening. It is tested on the 22 amino acid residue peptide motilin, selectively 13 C labeled in the ortho positions in the ring of the single tyrosine residue. In the approximation of an axially symmetric 13C CSA tensor, the symmetry axis of the CSA tensor makes an angle of 23 deg. ± 1 deg. to the 13 C-1H bond vector, and has a magnitude of 156 ± 5 ppm. This is in close agreement with solid-state NMR data on tyrosine powder [Frydman et al. (1992) Isr. J. Chem., 32, 161-164]
Primary Subject
Source
Copyright (c) 1999 Kluwer Academic Publishers; Country of input: International Atomic Energy Agency (IAEA)
Record Type
Journal Article
Journal
Journal of Biomolecular NMR; ISSN 0925-2738;
; v. 15(1); p. 27-37

Country of publication
AMINO ACIDS, ANGULAR MOMENTUM, CARBON ISOTOPES, CARBOXYLIC ACIDS, EVEN-ODD NUCLEI, FUNCTIONS, HYDROGEN ISOTOPES, HYDROXY ACIDS, ISOTOPES, LIGHT NUCLEI, MAGNETIC RESONANCE, NUCLEI, ODD-EVEN NUCLEI, ORGANIC ACIDS, ORGANIC COMPOUNDS, PARTICLE PROPERTIES, PROTEINS, RESONANCE, SPECTRAL FUNCTIONS, STABLE ISOTOPES, SYMMETRY
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