2-DIMENSIONAL AND 3-DIMENSIONAL P-31-DRIVEN NMR PROCEDURES FOR COMPLETE ASSIGNMENT OF BACKBONE RESONANCES IN OLIGODEOXYRIBONUCLEOTIDES

We describe a strategy for sequential assignment of P-31 and deoxyribo se H-1 NMR resonances in oligode-oxyribonucleotides. The approach is b ased on P-31-H-1 J-cross-polarization (heteroTOCSY) experiments, recen tly 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, 27271. Two-dimensional heteroTOCSY and heteroTOCSY-NO ESY 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 H-1 resona nces can be assigned as well. A new three-dimensional heteroTOCSY-NOES Y experiment is used for backbone proton 4', 5' and 5'' resonance assi gnments, completing assignments begun on this molecule in 1983 [Hare, D.R. et al. (1983) J. Mol Biol., 171, 3191. Numerical simulations of t he time dependence of coherence transfer aid in the interpretation of heteroTOCSY spectra of oligonucleotides and address the dependence of heteroTOCSY and related spectra on structural features of nucleic acid s. The possibility of a generalized backbone-driven H-1 and P-31 reson ance-assignment strategy for oligonucleotides is discussed.