Adinity-based DEL selection was performed using the C-terminal WD domain of WDR91 (residues 392-747) with an N-terminal His6-tag. The protein was immobilized in Ni 2+ -charged magnetic beads and incubated with the full OpenDEL TM library from HitGen. Unbound DEL members were washed away, and enriched compounds were heat-eluted and used as input for a second round of selection using fresh, immobilized WDR91. In total, three rounds of selection were performed. As a control, Ni 2+ -charged magnetic beads without protein were used to evaluate matrix binders (background control).