Quantitative comparison of experimental and simulated NOE intensities: correlation with accuracy of oligonucleotide structure determination.

The relation between the match of experimental and simulated NOE intensities with the accuracy of structure determination of oligonucleotides has been investigated. A hypothetical experimental spectrum of the oligonucleotide d(CCAACGTTGG) from its known X-ray crystallographic structure (Privé, G.G. et al. (1991) J. Mol. Biol., 217, 177-199) has been generated with simplifying assumptions of single correlation time, leakage rate etc., and this spectrum has been simulated imposing various constraints in a manner as one would do in a real case. The hypothetical spectrum represents the case of an infinitely good experimental spectrum and therefore the study of quality of fit against quality of structure represents the limiting case of real situations. It has been shown that even with a limited number of NOEs, it is possible to approach the correct structure of the molecule by demanding a highly accurate fit between experimental and simulated NOE intensities. Distance geometry calculations have been used to probe the extent of structural degeneracies in the NOE intensity matching exercise.