Practical aspects of 2D NMR for assigning the non-exchangeable protons in DNA-RNA fragments.

Using the branched trimer A2'-5'A3'-5'A as an example, different 2D NMR experiments such as homonuclear correlations via single-quantum coherence, double-quantum filtration via double-quantum coherence, isotropic mixing, relayed connectivities, cross relaxation and 31P/1H correlations are presented together with the corresponding spectra. The discussion pointed out the advantages and the difficulties of 14 pulse sequences, used for assigning non-exchangeable protons in DNA or RNA fragments. The emphasis has been put on the methodological aspects of 2D NMR as a simple technique, allowing an easier assimilation of the new coming 2D NMR pulse sequences.