Lincoln Scott - Measurement of long-range 1H-19F scalar coupling constants and their glycosidic torsion dependence in 5-fluoropyrimidine-substituted RNA.

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      J Am Chem   Soc. 2006 May 3;128(17):5851-8.


      Long-range scalar 5J(H1',F) couplings were observed in   5-fluoropyrimidine-substituted RNA. We developed a novel   S3E-19F-alpha,beta-edited NOESY experiment for quantitation of   these long-range scalar 5J(H1',F) couplings, where the   J-couplings can be extracted from inspection of intraresidual   (H1',H6) NOE cross-peaks. Quantum chemical calculations were   exploited to investigate the relation between scalar couplings   and conformations around the glycosidic bond in oligonucleotides.   The theoretical dependence of the observed 5J(H1',F) couplings on   the torsion angle chi can be described by a generalized Karplus   relationship. The corresponding density functional theory (DFT)   analysis is outlined. Additional NMR experiments facilitating the   resonance assignments of 5-fluoropyrimidine-substituted RNAs are   described, and chemical shift changes due to altered shielding in   the presence of fluorine-19 (19F) are presented.

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