N-15 CHEMICAL-SHIFT TENSORS IN NUCLEIC-ACID BASES

This paper presents measurements of the principal values of the N-15 c hemical shift tensors in adenine, cytosine, guanine, and thymine. The assignment of the solid-state NMR resonances was done using the liquid values in the corresponding nuclesides and the results of quantum mec hanical calculations of the N-15 tensors, The calculations were also u sed to assign the orientation of the principal axes of the tensors and to evaluate the effect of intermolecular interactions on the N-15 che mical shift tensors of the nucleic acid bases. The results indicate th at calculations including intermolecular interactions produce results in better agreement with the experimental values than those in which t hese interactions are neglected.