Similarities between intra- and intermolecular hydrogen bonds in RNA kissing complexes found by means of cross-correlated relaxation

The bond lengths and dynamics of intra- and intermol. hydrogen bonds in an RNA kissing complex have been characterized by detg. the NMR relaxation rates of various double- and triple-quantum coherences that involve an imino proton and two neighboring nitrogen-15 nuclei belonging to opposite bases. New expts. allow one to det. the chem. shift anisotropy of the imino protons. The bond lengths derived from dipolar relaxation and the lack of modulations of the nitrogen chem. shifts indicate that the intermol. hydrogen bonds which hold the kissing complex together are very similar to the intramol. hydrogen bonds in the double-stranded stem of the RNA.