An effective pulse sequence for detecting a ligand binding with a protein receptor using a WET sequence and the repeated Z-filters.

WaterLOGSY and STD experiments are widely used as NMR-based screening techniques in drug research. In the present study, an improved STD pulse sequence was developed, and its efficiency and applicability of observing the ligand signals were evaluated compared with the WaterLOGSY experiment. A combination of presaturation, a WET sequence and subsequent repeated Z-filters can provide the most effective water suppression, which is incorporated into the STD pulse sequence. In a sample solution of tryptophan and glucose in the presence of human serum albumin, the improved STD experiment only succeeded in selective detections of the bound ligand signals, even resonating close to water.