Function-First Molecular Glue Discovery

Molecular glues modulate protein proximity but have resisted direct, function first discovery. We define physicochemical features that distinguish true glues from non-glues by comparing their affinities in ternary versus binary protein complexes. Using these criteria, we coupled high-throughput chemical synthesis with affinity-selection mass spectrometry to screen >20,000 unpurified reaction mixtures. Kinetic profiling of protein pairs within these crude libraries enabled rapid, mechanism anchored triage of candidates. From this screen, we identified a molecular glue degrader, and orthogonal assays confirmed that ternary-complex stabilization underlies its activity. Our results establish a practical framework for de novo glue discovery that operates on crude mixtures, links readouts directly to ternary complex energetics, and scales with synthesis throughput. This approach provides a general roadmap for accelerating molecular glue identification and mechanistic validation.