TY - JOUR
T1 - Efficient multispin homonuclear double-quantum recoupling for magic- angle spinning NMR
T2 - 13C-13C correlation spectroscopy of U-13C- erythromycin A
AU - Rienstra, Chad M.
AU - Hatcher, Mary E.
AU - Mueller, Leonard J.
AU - Sun, Boqin
AU - Fesik, Stephen W.
AU - Griffin, Robert G.
PY - 1998/10/21
Y1 - 1998/10/21
N2 - We introduce a radio frequency (rf) pulse sequence for efficient homonuclear double-quantum dipolar recoupling under magic-angle spinning NMR. The sequence is optimized for two-dimensional double-quantum 13C-13C chemical shift correlation spectroscopy in multiple spin systems, such as the U-13C-labeled antibiotic erythromycin A. Spin systems such as this display a wide range of isotropic and anisotropic chemical shifts and, therefore, require a broadband dipolar recoupling sequence that minimizes the errors arising from the interaction of chemical shifts and rf inhomogeneity. The sequence should also preserve the theoretical efficiency over the powder average (~73%) provided by the C7 experiment of Levitt and co-workers (Lee, Y. K.; Kurur, N. D.; Helmle, M.; Johannessen, O. G.; Nielsen, N. C.; Levitt, M. H. Chem. Phys. Lett. 1995, 242, 304-309). We satisfy these criteria by combining the standard C7 (2π(φ)-2π{f+180)) elements with π-pulse permuted elements (π(φ)-2π(φ+180)-π(φ), in analogy to the MLEV decoupling scheme) to remove error terms over a ±10% range of rf amplitude. The new sequence, which we refer to as CMR7 (combined MLEV refocusing and C7), yields for two-spin systems broadband double-quantum filtering efficiencies greater than 70%. For multispin systems, the improved polarization transfer efficiency results in greater cross-peak intensities, facilitating assignment of U-13C-labeled molecules in the solid state.
AB - We introduce a radio frequency (rf) pulse sequence for efficient homonuclear double-quantum dipolar recoupling under magic-angle spinning NMR. The sequence is optimized for two-dimensional double-quantum 13C-13C chemical shift correlation spectroscopy in multiple spin systems, such as the U-13C-labeled antibiotic erythromycin A. Spin systems such as this display a wide range of isotropic and anisotropic chemical shifts and, therefore, require a broadband dipolar recoupling sequence that minimizes the errors arising from the interaction of chemical shifts and rf inhomogeneity. The sequence should also preserve the theoretical efficiency over the powder average (~73%) provided by the C7 experiment of Levitt and co-workers (Lee, Y. K.; Kurur, N. D.; Helmle, M.; Johannessen, O. G.; Nielsen, N. C.; Levitt, M. H. Chem. Phys. Lett. 1995, 242, 304-309). We satisfy these criteria by combining the standard C7 (2π(φ)-2π{f+180)) elements with π-pulse permuted elements (π(φ)-2π(φ+180)-π(φ), in analogy to the MLEV decoupling scheme) to remove error terms over a ±10% range of rf amplitude. The new sequence, which we refer to as CMR7 (combined MLEV refocusing and C7), yields for two-spin systems broadband double-quantum filtering efficiencies greater than 70%. For multispin systems, the improved polarization transfer efficiency results in greater cross-peak intensities, facilitating assignment of U-13C-labeled molecules in the solid state.
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U2 - 10.1021/ja9810181
DO - 10.1021/ja9810181
M3 - Article
AN - SCOPUS:0032556234
SN - 0002-7863
VL - 120
SP - 10602
EP - 10612
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 41
ER -