The use of chemical shifts and their anisotropies in biomolecular structure determination

The existence of chemical shift dispersion is crucial for the application of NMR spectroscopy to biomolecules, but the direct interpretation of shift tensors in terms of structure and dynamics is often difficult. Proton shifts reflect environmental influences from nearby aromatic groups, metal sites or hydrogen-bonding partners. These effects can be reasonably modeled with empirical equations, but multiple contributions to shifts can be difficult to disentangle. Shifts for carbon and nitrogen generally reflect local bonding interactions, often in ways that allow the local structure to be inferred, The anisotropy of the shielding tensor is also of interest. it influences the resonance position in partially-ordered samples and has consequences for spin relaxation, even in isotropic systems. There has been recent progress in measuring and interpreting these anisotropies.