TR-FRET binding assay targeting unactivated form of Bruton's tyrosine kinase

Bruton's Tyrosine Kinase (BTK) is one of the crucial kinases for the B cell maturation and mast cell activation, and specific inhibitors of BTK are considered to be attractive targets in drug discovery research. In this Letter, we have designed and synthesized a new fluorescent probe for TR-FRET-based high-throughput screening, to identify compounds that preferentially bind to an inactive conformation of BTK which has a unique structural feature. A set of kinase-focused compound library was screened using this assay method, and compound 31 was successfully identified as a potent inhibitor which preferentially bind to the inactive conformation of BTK. These results suggest that this screening method has a great potential for the discovery of novel selective BTK inhibitors.