An Activity‐Based Imaging Probe for the Integral Membrane Hydrolase KIAA1363

Abstract

Activity-based protein profiling (ABPP) is a chemical proteomic platform for characterizing enzyme activities in native biological systems.[1–3] Original small-molecule probes for ABPP were designed to target large numbers of enzymes that share mechanistic and/or structural features. These efforts have yieled activity-based probes for many enzyme classes, including serine[4–5] and cysteine[6] hydrolases,oxidoreductases,[7] metalloproteases,[8] histone deacetylases,[9] kinases,[10] and glycosidases.[11–12] ABPP has been applied to discover enzyme activities that are deregulated in biological processes such as cancer[13] and infectious disease[14]. Configuring ABPP to operate in a competitive mode has further enabled the development of selective inhibitors to probe the function of disease-relevant enzymes in cell and animal models.[5–6][15] As biological studies using ABPP have evolved, the need for target-selective activity-based probes has also become apparent. The specificity of such probes opens up new biological applications, including direct spatial and temporal visualization of active enzymes in cells and tissues.[16–17] While attractive in principle, the development of protein-selective, activity-based imaging probes poses substantial technical challenges. Such a probe should ideally possess several features, including high selectivity for a single enzyme target, a reporter tag for imaging the probe-labeled enzyme, and suitable cell permeability and pharmacokinetic properties for in vivo studies. These objectives have, so far, been realized for only a handful of probes that label proteolytic enzymes[18] and whether they can be achieved for probes that target additional types of enzymes remains unknown.