PROTON NUCLEAR MAGNETITE RELAXATION OF 15N-LABELED NUCLEIC ACIDS VIA DIPOLAR COUPLING AND CHEMICAL SHIFT ANISOTROPY.

Article abstract of DOI:10.1021/ja00363a009

The authors have observed a differential in the relaxation rates of the imino proton NMR doublet of 3-**1**5N-substituted 2 prime ,3 prime ,5 prime -tri-O-benzoyluridine. The differential is ascribed to interference between dipole-dipole and chemical shift anisotropy mechanisms of relaxation. A value of 5. 7 ppm is derived for the proton chemical shift anisotropy, using a theory described in the Appendix, and due to M. Goldman. Differential broadening of **1**5N-substituted transfer ribonucleic acid by the same mechanism is shown to be quantitatively compatible with published observations. We conclude that these observations do not provide strong evidence of base-pair tautomerism.