Flipping the Switch: Innovations in Inducible Probes for Protein Profiling

Abstract

Over the past two decades, activity-based probes have enabled a range of discoveries, including the characterization of new enzymes and drug targets. However, their suitability in some labeling experiments can be limited by nonspecific reactivity, poor membrane permeability, or high toxicity. One method for overcoming these issues is through the development of "inducible" activity-based probes. These probes are added to samples in an unreactive state and require in situ transformation to their active form before labeling can occur. In this Review, we discuss a variety of approaches to inducible activity-based probe design, different means of probe activation, and the advancements that have resulted from these applications. Additionally, we highlight recent developments which may provide opportunities for future inducible activity-based probe innovations.

Figure 1

General scheme for activity-based probe labeling. (a) Traditional activity-based probe labeling. (b) Inducible activity-based probe labeling with a masked (unreactive) warhead which undergoes activation prior to labeling. (c) Inducible activity-based probe labeling with a warhead activated following binding to the protein of interest. (d) Affinity-based probe bearing a reversible binding motif and inducible cross-linking group.

Figure 2

Table of photoactivated and photocaged probes indicating mode of activation, target residue, and resultant protein–probe complex given as described in the denoted reference.

Figure 3

Table of agent-activated probes indicating mode of activation, target residue, and resultant protein–probe complex given as described in the denoted reference.

Figure 4

Table of cell activated probes indicating mode of activation, target residue, and resultant protein–probe complex given as described in the denoted reference.

Figure 5

Table of mechanism-based probes and binding-associated activation of latent electrophilic probes indicating mode of activation by a protein of interest, activated species, and resultant protein–probe complex described in the denoted reference.