Structural analysis of uniformly (13)C-labelled solids from selective angle measurements at rotational resonance

Patching, Simon G and Edwards, Rachel and Middleton, David A (2009) Structural analysis of uniformly (13)C-labelled solids from selective angle measurements at rotational resonance. June 2002. ISSN 1460-4582, 199 (2). pp. 242-6. ISSN 0893-3200

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Abstract

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.

Item Type:
Journal Article
Journal or Publication Title:
June 2002. ISSN 1460-4582
Uncontrolled Keywords:
/dk/atira/pure/subjectarea/asjc/3200
Subjects:
ID Code:
66271
Deposited By:
Deposited On:
17 Sep 2013 08:03
Refereed?:
Yes
Published?:
Published
Last Modified:
01 Jan 2020 08:36