Cover Feature: α‐Methylene‐β‐Lactone Scaffold for Developing Chemical Probes at the Two Ends of the Selectivity Spectrum (ChemBioChem 3/2021)

Multi-electrophilic yet compact, the rigid α-methylene-β-lactone (MeLac) warhead creates new opportunities to probe the live-cell proteome. The MeLac probe reacts with five types of nucleophile on all seven classes of enzymes. Protein structures show reacting residues in red and the probe in blue. On the upper left, a protein directs the tethering of an affinity ligand (yellow) to the probe. More information can be found in the full paper by X. Yao et al.