HSQC

H—N HSQC

Chemicals labelled with N isotope are relatively inexpensive, and the N HSQC is a sensitive experiment whereby a spectrum can be acquired in a relatively short time, the N HSQC is therefore often used to screen candidates for their suitability for structure determination by NMR, as well as optimization of the sample conditions. The time-consuming process of structure determination is usually not undertaken until a good HSQC spectrum can be obtained. The HSQC experiment is also useful for detecting binding interface in protein-protein interaction, as well the interactions with ligands such as drugs. By comparing the HSQC of the free protein with the one bound to the ligand, changes in the chemical shifts of some peaks may be observed, and these peaks are likely to lie on the binding surface where the binding perturbed their chemical shifts. The N HSQC may also be used in relaxation analysis in the studies of molecular dynamics of proteins, the determination of ionization constant, and other studies.