A strategy for high-throughput assay development using leads derived from nuclear magnetic resonance-based screening

A strategy is described for the development of high-throughput screening assays against targets of unknown function that involves the use of nuclear magnetic resonance (NMR) spectroscopy. Using this approach, molecules that bind to the protein target are identified from an NMR-based screen of a library of substrates, cofactors, and other compounds that are known to bind to many proteins and enzymes. Once a ligand has been discovered, a fluorescent or radiolabeled analog of the ligand is synthesized that can be used in a high-throughput screen. The approach is illustrated in the development of a high-throughput screening assay against HI-0033, a conserved protein from Haemophilus influenzae whose function is currently unknown. Adenosine was found to bind to HI-0033 by NMR, and fluorescent analogs were rapidly identified that bound to HI-0033 in the submicromolar range. Using these fluorescent compounds, a fluorescence polarization assay was developed that is suitable for high-throughput screening and obtaining detailed structure-activity relationships for lead optimization.