Characterization of the Binding of Small Molecules to Intrinsically Disordered Proteins

Intrinsically disordered proteins (IDPs) comprise a large fraction of eukaryotic proteomes. IDPs are prevalent in cellular regulation, signaling networks, and disease pathways. The abundance and activity of IDPs is tightly controlled at multiple levels, and their dysregulation is associated with disease. Because of the importance of IDPs in both normal and disease states of the cell, IDPs are attractive targets for modulation by small molecules both to understand their biology and to provide potential drug leads. Multiple screens have successfully identified small molecules that bind to IDPs. Here, we describe how surface plasmon resonance, NMR, and fluorescence methods can be used to characterize the direct binding affinity between small molecules and IDPs. We describe how these techniques can contribute to identifying previously unknown small-molecule binding sites on IDPs.