PR002550 (Project)

Description:We report an enantioselective protein affinity selection mass spectrometry screening approach (EAS-MS) that enables the detection of weak binders, informs on selectivity, and generates orthogonal confirmation of binding. After method development with control proteins, we screened 31 human proteins against a designed library of 8,210 chiral compounds. A total of 16 binders to 12 targets, including many proteins predicted to be “challenging to ligand”, were discovered and confirmed in orthogonal biophysical assays. Seven binders to six targets bound in an enantioselective manner, with KD values ranging from 3 to 50 µM. Binders for four targets (DDB1, WDR91, WDR55, and HAT1) were selected for in-depth characterization using X-ray crystallography. In all four cases, the mechanism for enantioselectivity was readily explained. We conclude EAS-MS can be used to identify and characterize selective and weakly binding ligands for novel protein targets with unprecedented throughput and sensitivity.