Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Structural analysis of uniformly (13)C-labelled solids from selective angle measurements at rotational resonance
AU - Patching, Simon G
AU - Edwards, Rachel
AU - Middleton, David A
PY - 2009/8
Y1 - 2009/8
N2 - We demonstrate that individual H-C-C-H torsional angles in uniformly labelled organic solids can be estimated by selective excitation of (13)C double-quantum coherences under magic-angle spinning at rotational resonance. By adapting a straightforward one-dimensional experiment described earlier [T. Karlsson, M. Eden, H. Luhman, M.H. Levitt, J. Magn. Reson. 145 (2000) 95-107], a double-quantum filtered spectrum selective for Calpha and Cbeta of uniformly labelled L-[(13)C,(15)N]valine is obtained with 25% efficiency. The evolution of Calpha-Cbeta double-quantum coherence under the influence of the dipolar fields of bonded protons is monitored to provide a value of the Halpha-Calpha-Cbeta-Hbeta torsional angle that is consistent with the crystal structure. In addition, double-quantum filtration selective for C6 and C1' of uniformly labelled [(13)C,(15)N]uridine is achieved with 12% efficiency for a (13)C-(13)C distance of 2.5A, yielding a reliable estimate of the C6-H and C1'-H projection angle defining the relative orientations of the nucleoside pyrimidine and ribose rings. This procedure will be useful, in favourable cases, for structural analysis of fully labelled small molecules such as receptor ligands that are not readily synthesised with labels placed selectively at structurally diagnostic sites.
AB - We demonstrate that individual H-C-C-H torsional angles in uniformly labelled organic solids can be estimated by selective excitation of (13)C double-quantum coherences under magic-angle spinning at rotational resonance. By adapting a straightforward one-dimensional experiment described earlier [T. Karlsson, M. Eden, H. Luhman, M.H. Levitt, J. Magn. Reson. 145 (2000) 95-107], a double-quantum filtered spectrum selective for Calpha and Cbeta of uniformly labelled L-[(13)C,(15)N]valine is obtained with 25% efficiency. The evolution of Calpha-Cbeta double-quantum coherence under the influence of the dipolar fields of bonded protons is monitored to provide a value of the Halpha-Calpha-Cbeta-Hbeta torsional angle that is consistent with the crystal structure. In addition, double-quantum filtration selective for C6 and C1' of uniformly labelled [(13)C,(15)N]uridine is achieved with 12% efficiency for a (13)C-(13)C distance of 2.5A, yielding a reliable estimate of the C6-H and C1'-H projection angle defining the relative orientations of the nucleoside pyrimidine and ribose rings. This procedure will be useful, in favourable cases, for structural analysis of fully labelled small molecules such as receptor ligands that are not readily synthesised with labels placed selectively at structurally diagnostic sites.
KW - Algorithms
KW - Carbon Isotopes
KW - Computer Simulation
KW - Magnetic Resonance Spectroscopy
KW - Models, Chemical
KW - Rotation
KW - Staining and Labeling
U2 - 10.1016/j.jmr.2009.05.002
DO - 10.1016/j.jmr.2009.05.002
M3 - Journal article
C2 - 19487142
VL - 199
SP - 242
EP - 246
JO - June 2002. ISSN 1460-4582
JF - June 2002. ISSN 1460-4582
SN - 0893-3200
IS - 2
ER -