Cell-Active, Arginine-Targeting Irreversible Covalent Inhibitors for Non-Kinases and Kinases

Targeted covalent inhibitors (TCIs) play an essential role in the fields of kinase research and drug discovery. Most existing TCIs are however cysteine- or lysine-reactive, thus severely limiting their potential applications. New types of TCIs capable of covalently targeting other nucleophilic amino acids that are readily available in proteins are urgently needed. We report herein a glyoxal-based, arginine-reactive strategy to generate potent and selective small-molecule TCIs of Mcl-1 (an important anti-apoptotic protein) by selectively targeting the conserved arginine (R263) in the protein. We further validated the generality of this strategy by developing glyoxal-based, irreversible covalent inhibitors of AURKA (a cancer-related kinase) that showed exclusive reactivity with a solvent-exposed arginine (R220) of this enzyme. We showed the resulting compounds were potent, selective and cell-active, capable of covalently engaging endogenous AURKA in MV-4-11 cells with long residence time. Finally, we showed the potential application of glyoxal-based TCIs in targeting an acquired drug-resistance mutant of ALK kinase (G1202R).