Automated Protein–Ligand Interaction Screening by Mass Spectrometry

Identifying protein–ligand binding interactions is a key step during early-stage drug discovery. Existing screening techniques are often associated with drawbacks such as low throughput, high sample consumption, and dynamic range limitations. The increasing use of fragment-based drug discovery (FBDD) demands that these techniques also detect very weak interactions (mM K D values). This paper presents the development and validation of a fully automated screen by mass spectrometry, capable of detecting fragment binding into the millimolar K D range. Low sample consumption, high throughput, and wide dynamic range make this a highly attractive, orthogonal approach. The method was applied to screen 157 compounds in 6 h against the anti-apoptotic protein target Bcl-xL. Mass spectrometry results were validated using STD-NMR, HSQC-NMR, and ITC experiments. Agreement between techniques suggests that mass spectrometry offers a powerful, complementary approach for screening.