Proteome-wide profiling of the selectivity of diverse electrophiles (part 2)

Targeted covalent inhibitors (TCIs) are established as powerful entities in drug discovery, but their application has so far mainly been limited to addressing cysteine. Competitive, residue-specific proteomics has been instrumental to streamline covalent drug discovery targeting cysteine. Several probes have recently been described to monitor other amino acids using this technology and many more electrophiles exist to modify proteins. Nevertheless, a direct, proteome-wide comparison of the amino acid selectivity of diverse probes is still entirely missing. Here, we developed a completely unbiased workflow to analyse electrophile selectivity proteome-wide and applied it to directly compare 54 alkyne probes containing diverse reactive groups. In this way, we verified and newly identified probes to monitor nine different amino acids as well as the N-terminus proteome-wide. This selection e.g. includes the first probes to globally monitor tryptophan, histidine and arginine as well as novel tailored probes for methionine, aspartate and glutamate.