Chemical shift changes of the free versus complexed protein in, for instance, 2D¹H-¹⁵N HSQC/HMQC ( 94PRO70, 97NAT717, 97JB389, 97JACS7589, 98JACS30, 99JMC2315, 00JB139, 00JB189-18 and 02JACS1234) or in 3D HNCO ( 96NAT995) spectra is one of the most sensitive method to monitor specific protein-ligand complex over a broad affinity range.

In addition, the binding site of the ligand can be localized on the protein surface if the resonances of the protein are assigned. This is the basis of the so-called SAR by NMR and NMR screening ( 96SCI1531, 97JACS5818, 97JMC3144, 97ANG829, 00JB319-18, 00JMC3443).

A ¹H/¹³C approach based on selective ¹³C-labeling ( 00JACS7898 and 03JACS2892) and a ¹H/¹⁵N approach based on selective ¹⁵N-labeling ( 02JACS2446, 03JACS14250 and 03JACS10941) have been reported.

However, no information on the orientation of the ligand in the binding site is obtained and ligand-induced conformational changes of the protein can complicate data interpretation. The use of differential chemical shifts has been proved very useful to determine the binding site location and also the orientation of the ligand in the binding pocket ( 00JACS1241). This approach involves the comparison of chemical shifts changes of a protein induced by a series of closely related ligands.

Novel methods designed for quantitative analysis of such chemical shift perturbated NMR spectra has been reported ( 04JB491-29)

ALARM NMR: A method to detect reactive false positives using 13C chemical shift changes ( 05JACS217)

Automated analysis of large sets of 2D HSQC spectra ( 02JMC5649)