Selecting a DNA-Encoded Chemical Library against Non-immobilized Proteins Using a "Ligate-Cross-Link-Purify" Strategy.

DNA-encoded chemical libraries (DELs) have recently emerged and become an important technology platform in biomedical research and drug discovery. DELs containing large numbers of compounds can be prepared and selected against biological targets to discover novel ligands and inhibitors. In practice, DELs are usually selected against purified and immobilized proteins using the typical "bind-wash-elute" protocol; however, selection methods compatible with non-immobilized proteins would be able to greatly expand the target scope of DELs beyond purified proteins to more-complex and biologically relevant targets. Using a novel "ligate-cross-link-purify" strategy, we report here a method capable of selecting DELs against unmodified and non-immobilized protein targets. In addition, this method has shown excellent capability in identifying binders with moderate and weak affinities.