New cysteine-reactive probes to expand the pool of ligandable cysteines for biological studies and drug development
Understanding functions and reactivity of cysteines on proteins have arouse lots of interest. This is not only for getting better ideas on biological processes initiated/regulated by proteins containing these functional cysteines, but also for the huge potentials to develop drug compounds targeting these cysteines for therapy.
Activity-based protein profiling (ABPP) is one of the most widely used platforms for proteome-wide cysteine profiling to identify functional cysteines. Cysteine-reactive probe is the key component in ABPP platform and can define the pool of ligandable cysteines and hence the population of proteins that can be targeted by covalent ligands. The conventional cysteine-reactive probe, iodoacetamide-alkyne (IAA), shows only fair reaction kinetics and selectivity with cysteine. Together with its high cellular toxicity and low biostability, this limits the full potential of ABPP platform for biological studies and drug research.
Against this backdrop, our lab is developing novel cysteine-reactive probes which show better cysteine reaction kinetics and selectivity. Together with their high biostability and low cytotoxicity, they have been found to capture more cysteines than IAA in cell lysates and live cells, in both gel-based and fluorescence imaging experiments. More interestingly, in MS experiments, our probes capture a larger and a significantly different population of cysteines than IAA. This should expand the pool of ligandable hotspots in whole-proteome cysteine profiling experiments, and facilitates further research and study on the development of new covalent ligands and potential lead compounds for targeting these new proteins for therapy.