A proton-relaxation-time study of the conformation of some purine and pyrimidine 5'-nucleotides in aqueous solution.

The measurement of proton relaxation time T1 in a series of purine and pyrimidine 5'-nucleotides has been carried out to investigate their conformation in dilute neutral aqueous solutions. The interpretation of relaxation data has been performed with the help of computer calculations taking into account the different conformers of the ribose ring and of the exocyclic group. It has been found that all nucleotides under study show nearly the same preferential orientations of the base defined by gamma0 = 70 degrees +/- 10 degrees in the syn range. A more elaborate treatment, using an angular distribution derived from calculated potentials on 5" -GMP gives theoretical relaxation times in close agreement with experimental ones.