| A general goal of NMR studies of biomolecules is to obtain as accurate as possible data that can characterize the structure and/or dynamics of the studied system. A necessary first step in any NMR study is the resonance assignment. For this purpose, the methods that rely on through-bond interactions are preferable. Methods to allow complete resonance assignment of both proteins and nucleic acids have been developed by now. Today, the task is to improve the sensitivity and resolution of the methods to allow application to bimolecular systems of increasing complexity. No matter how sophisticated assignment methods may be, the structure calculations relied up to recently mostly on restraints derived from NOE spectra that include only local interactions. Therefore, additional sources of structural constraints are being investigated such as residual dipolar couplings and structural dependence of either isotropic chemical shifts or chemical shift anisotropy. New efficient methods are therefore needed to measure small changes in spin-spin couplings induced by oriented media and to obtain accurate values of chemical shifts of as many nuclei in the molecule as possible. |
