10.1021/ja0367041.s001 Elke Duchardt Elke Duchardt Christian Richter Christian Richter Oliver Ohlenschläger Oliver Ohlenschläger Matthias Görlach Matthias Görlach Jens Wöhnert Jens Wöhnert Harald Schwalbe Harald Schwalbe Determination of the Glycosidic Bond Angle χ in RNA from Cross-Correlated Relaxation of CH Dipolar Coupling and N Chemical Shift Anisotropy American Chemical Society 2004 angle χ heteronuclear NMR pulse sequence RNA structure calculations CH Dipolar glycosidic torsion angle χ 13 C 3 J NMR experiments 10 degrees mer HCN Glycosidic Bond Angle χ torsion angle information determination N Chemical Shift Anisotropy 15 N chemical shift tensors 2004-02-25 00:00:00 Journal contribution https://acs.figshare.com/articles/journal_contribution/Determination_of_the_Glycosidic_Bond_Angle_in_RNA_from_Cross_Correlated_Relaxation_of_CH_Dipolar_Coupling_and_N_Chemical_Shift_Anisotropy/3348613 A new heteronuclear NMR pulse sequence, the quantitative Γ(HCN) experiment, for the determination of the glycosidic torsion angle χ in <sup>13</sup>C,<sup>15</sup>N-labeled oligonucleotides is described. The Γ(HCN) experiment allows measurement of CH dipole−dipole, N chemical shift anisotropy cross-correlated relaxation rates ( and for pyrimidines and and for purines). A nucleotide-specific parametrization for the dependence of these Γ-rates on χ based on <sup>15</sup>N chemical shift tensors determined by solid-state NMR experiments on mononucleosides (Stueber, D.; Grant, D. M. <i>J. Am. Chem. Soc</i>. <b>2002</b>, <i>124</i>, 10539−10551) is presented. For a 14-mer and a 30-mer RNA of known structures, it is found that the Γ(HCN) experiment offers a very sensitive parameter for changes in the angle χ and allows restraining of χ with an accuracy of around 10 degrees for residues which do not undergo conformational averaging. Therefore, the Γ(HCN) experiment can be used for the determination of χ in addition to data derived from <sup>3</sup><i>J</i>(C,H)-coupling constants. As shown for the 30-mer RNA, the derived torsion angle information can be incorporated as additional restraint, improving RNA structure calculations.