A cell-based ultra-high-throughput screening assay for identifying inhibitors of D-amino acid oxidase.

Enzymes are often considered less "druggable" targets than ligand-regulated proteins such as G-protein-coupled receptors, ion channels, or other hormone receptors. Reasons for this include cellular location (intracellular vs. cell surface), typically lower affinities for the binding of small molecules compared to ligand-specific receptors, and binding (catalytic) sites that are often charged or highly polar.