STD-NMR: application to transient interactions between biomolecules-a quantitative approach.

Saturation transfer difference NMR (STD NMR) spectroscopy is one of the most powerful NMR techniques for detection and characterization of transient (fast) receptor-ligand interactions in solution. By observing the signals of a small molecule (ligand) with spectroscopic properties suitable for high-resolution studies, irrespective of receptor size, STD NMR enables quantitative structural and affinity information to be obtained about the molecular recognition process under study. Approximately one decade after its introduction, the technique has reached maturity, and is highly robust and useful. The objective of this article is to review the current status of this powerful technique, with particular emphasis on quantitative applications, within the framework of the (bio-)chemistry of molecular recognition.