Activity-Based Protein Profiling: From Chemical Novelty to Biomedical Stalwart.

Biological systems often respond to environmental changes by rapidly altering the activity of specific enzymes: for example through desequesterization of enzyme activities by dissociation from inhibitors, activation/deactivation through posttranslational modification, or relocation of the enzyme to different organelles. This means that expression levels of enzymes do not necessarily correlate with the activities observed for these enzymes. In this chapter we review some of the approaches used to selectively image only the active sub-populations of given enzymes, the so-called activity-based protein profiling. A focus lies on recent developments that are taking this approach from chemical novelty to biochemical stalwart.