Two- and three-dimensional 31P-driven NMR procedures for complete assignment of backbone resonances in oligodeoxyribonucleotides

Summary We describe a strategy for sequential assignment of ³¹P and deoxyribose ¹H NMR resonances in oligodeoxyribonucleotides. The approach is based on ³¹P–¹H J-cross-polarization (hetero TOCSY) experiments, recently demonstrated for the assignment of resonances in RNA [Kellogg, G.W. (1992) J. Magn. Reson., 98, 176; Kellogg, G.W. et al. (1992) J. Am. Chem. Soc., 114, 2727]. Two-dimensional hetero TOCSY and hetero TOCSY-NOESY experiments are used to connect proton spin systems from adjacent nucleotides in the dodecamer d(CGCGAATTCGCG)₂ entirely on the basis of through-bond scalar connectivities. All phosphorus resonances of the dodecamer are assigned by this method, and many deoxyribose ¹H resonances can be assigned as well. A new three-dimensional hetero TOCSY-NOESY experiment is used for backbone proton 4, 5 and 5 resonance assignments, completing assignments begun on this molecule in 1983 [Hare, D.R. et al. (1983) J. Mol. Biol., 171, 319]. Numerical simulations of the time dependence of coherence transfer aid in the interpretation of hetero TOCSY spectra of oligonucleotides and address the dependence of hetero TOCSY and related spectra on structural features of nucleic acids. The possibility of a generalized backbone-driven ¹H and ³¹P resonance-assignment strategy for oligonucleotides is discussed.To whom correspondence should be addressed.