The variation of the proton chemical shifts due to the formation of intermolecular hydrogen bonds is computed for a number of complexes which can be formed between the bases of the nucleic acids. The shifts expected for the isolated base pairs, in particular for the G-N1 H, T(or U)-N3 H protons and the protons of the amino groups of A, G and C, when combined with previous computations on the shifts to be expected upon base stacking, may enable a refined analysis of the high resolution NMR spectra of self complementary polynucleotides or tRNAs. Two examples are presented of a direct computation of proton shifts associated with helix-coil transitions, helpful for deducing the helical structure in solution.
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