Calculation of Structural Behavior of Indirect NMR Spin-Spin Couplings in the Backbone of Nucleic Acids.
Sychrovsky, V.; Vokacova, Z; Sponer, J. etc.,
Journal of Physical Chemistry B, 110 22894 - 22903 (2006)
Calculated indirect NMR spin-spin coupling constants (J-couplings) between P-31, C-13, and H-1 nuclei were related to the backbone torsion angles of nucleic acids (NAs), and it was shown that J-couplings can facilitate accurate and reliable structural interpretation of NMR measurements and help to discriminate between their distinct conformational classes. A proposed stepwise procedure suggests assignment of the J-couplings to torsion angles from the sugar part to the phosphodiester link. Some J-couplings show multidimensional dependence on torsion angles, the most prominent of which is the effect of the sugar pucker. J-couplings were calculated in 16 distinct nucleic acid conformations, two principal double-helical DNAs, B- and A-, the main RNA form, A-RNA, as well as in 13 other RNA conformations. High-level quantum mechanics calculations used a baseless dinucleoside phosphate as a molecular model, and the effect of solvent was included. The predicted J-couplings correlate reliably with available experimental data from the literature.