Covalent targeting leads to the development of LIMK1 isoform-selective inhibitors

SM311 is a covalent LIMK1 inhibitor. To verify the specificity of SM311 towards LIMK1, a chemoproteomic competition experiment was set up with a biotin adduct of SM311, namely SM429. This adduct was immobilised on Streptactin beads and used to enrich proteins binding to SM429. Preincubation with an excess of SM311 was used as control to outcompete and block the binding of SM429. In the competition setup we show that LIMK1 is depleted if SM311 is added in excess but also identified two additional kinase off-targets that required further profiling.