Determination of the glycosidic torsion angels in uniformly C-13 labeled nucleic acids from vicinal coupling constants 3J(C2/4-H1') and 3J(C6/8-H1')
| Authors | |
|---|---|
| Year of publication | 2002 |
| Type | Article in Periodical |
| Magazine / Source | Journal of Biomolecular NMR |
| MU Faculty or unit | |
| Citation | |
| Field | Physical chemistry and theoretical chemistry |
| Keywords | DNA; glycosidic bond; Karplus equation; NMR; quadruplex; scalar coupling |
| Description | A two-dimensional, quantitative J-correlation NMR experiment for precise measurements of the proton-carbon vicinal coupling constants 3JC2/4-H1' and 3JC6/8-H1' in uniformly 13C-labeled nucleic acids is presented. To reduce loss of signal due to 1H -13C dipole-dipole relaxation, a multiple-quantum constant time experiment with appropriately incorporated band selective 1H and 13C pulses was applied. The experiment is used to obtain the 3JC2/4-H1' and 3JC6/8-H1' coupling constants in a uniformly 13C, 15N-labeled [d(G4T4G4)]2 quadruplex. The measured values and glycosidic torsion angles in the G-quadruplex, obtained by restrained molecular dynamics with explicit solvent using the previously published restraints, along with selected data from the literature, are used to check and modify existing parameters of the Karplus equations. The parameterizations obtained using glycosidic torsion angles derived from the original solution and recently determined X-ray structures are also compared. |
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