Microplate-Based Enzymatic Activity Assay Protocol Powered by Activity-Based Probes

In the pursuit of innovative therapeutics, understanding enzyme inhibitors' mechanisms is pivotal. In this chapter, we explore a novel methodology that combines the precision of Activity-Based Protein Profiling (ABPP) with the efficiency of microplate assays to unveil enzyme inhibition profiles. Central to this approach is the use of competitive ABPP, which utilizes an in-house fluorophosphonate-based probe, as an example of an electrophilic probe, to directly observe the interactions between inhibitors and pig liver esterase, chosen as a model serine hydrolase. This method leverages the scalability of 96-well microplates to facilitate rapid and sensitive screening across various molecules, marking a significant advancement in the field of drug discovery. By applying this technique, we not only expedite the identification of potential drug candidates but also gain deeper insights into their modes of action, thereby enhancing our understanding of their therapeutic potential. This chapter provides a comprehensive protocol for the synthesis of ABPP probes, preparation of enzyme solutions, and execution of plate-based assays, offering a robust platform for the development of novel enzyme inhibitors. Through this innovative approach, we aim to pave the way for a new tool for the next-generation drug discovery, highlighting the transformative potential of chemical proteomics in unveiling the intricate dynamics of enzyme modulation.