Enzymatic Cleavage of Double‐Stranded DNA‐Encoded Libraries (DELs) to Single‐Stranded DELs with Compounds at the 3′ End: Its Application in Photo‐Crosslinking Selection

DNA-encoded library (DEL) technology is a crucial tool in pharmaceutical research, rapidly identifying compounds that bind to a target of interest from an extensive pool of compounds. In this study, we propose a new method for generating single-stranded DELs (ssDELs) with compounds at the 3' end. The introduction of uniquely designed hairpin-shaped headpieces containing deoxyuridine (NC-HP) and the use of a cleavage enzyme facilitate the conversion from double-stranded DELs (dsDELs) to such ssDELs. Moreover, Klenow fill-in provides the dsDELs with photo-crosslinkers covalently linked to the coding region, which exhibit durability even under stringent washing conditions and enable photo-crosslinking with a high signal-to-noise ratio, as also confirmed in cell-based photo-crosslinking selections.