NMR Studies of Nucleic Acids and Their Complexes

Abstract

As the study of biological processes has progressed to the molecular level understanding of the underlying mechanisms has required determination of the three-dimensional structures of the molecules involved, their ability to undergo structural interconversions, and the interactions among them. For molecules that form highly ordered crystals, X-ray diffraction provides very precise structural information. However, there are cases in which the crystal packing affects the structure, and there are many molecules for which crystals have not been obtained. With the development of multidimensional experiments and high-field spectrometers, NMR spectroscopy has become an important alternative for structure determination. NMR has the obvious advantages that crystals are not needed, rather only moderately concentrated solutions, and that it is possible to deal quite well with complications such as interconverting conformers. In addition, the solution conditions can be varied widely, changing solvent composition, ions, pH, temperature and so forth without worrying about disrupting the crystallization conditions. These advantages have made NMR an attractive alternative to crystallography for determination of biomolecular structures (Wüthrich, 1986). However, it is still important to understand that there are significant differences between the two methods, which should be considered when interpreting data. As is usually true, it is best if results can be determined on the same system by both of these methods, and then compared.