A protein recycling system for nuclear magnetic resonance-based screening of drug candidates.

A sample-treating system for nuclear magnetic resonance (NMR)-based interaction screening between drug candidates (small molecules) and a protein of interest was developed by applying high-performance liquid chromatography (HPLC) technology. The system prepares a test solution by mixing a (15)N-labeled protein solution and a solution of each candidate compound, loads it to a flow cell-type NMR probe, and recycles the protein after the data acquisition. The system was designed to behave differently according to the information obtained in NMR measurements. In a test operation with a 100-compound library, the system could single out known interacting substances properly. Recovery values of the protein and one representative compound were 75 and 71%, respectively, and the recovered protein was found intact as intended.