Activity-based proteomics

Activity-based proteomics, or activity-based protein profiling (ABPP) is a functional proteomic technology that uses chemical probes that react with mechanistically related classes of enzymes.^[1]

Fluorophosphonate-rhodamine (FP-Rhodamine) activity-based probe for profiling of the serine hydrolase superfamily. In this probe the fluorophosphonate is the reactive group (RG) as it binds irreversibly to the active-site serine nucleophile of serine hydrolases and the tag is rhodamine, a fluorophore for in-gel visualization.

Description

The basic unit of ABPP is the probe, which typically consists of two elements: a reactive group (RG, sometimes called a "warhead") and a tag. Additionally, some probes may contain a binding group which enhances selectivity. The reactive group usually contains a specially designed electrophile that becomes covalently-linked to a nucleophilic residue in the active site of an active enzyme. An enzyme that is inhibited or post-translationally modified will not react with an activity-based probe. The tag may be either a reporter such as a fluorophore or an affinity label such as biotin or an alkyne or azide for use with the Huisgen 1,3-dipolar cycloaddition (also known as click chemistry).^[2]

Advantages

A major advantage of ABPP is the ability to monitor the availability of the enzyme active site directly, rather than being limited to protein or mRNA abundance. With classes of enzymes such as the serine hydrolases^[3] and metalloproteases^[4] that often interact with endogenous inhibitors or that exist as inactive zymogens, this technique offers a valuable advantage over traditional techniques that rely on abundance rather than activity. Furthermore, ABPP could be used to target specific proteins which were previously viewed as undruggable targets.^[5]

Multidimensional protein identification technology

In-gel ABPP using probes with different fluorophores in the same lane to simultaneously profile differences in enzyme activities

In recent years ABPP has been combined with tandem mass spectrometry enabling the identification of hundreds of active enzymes from a single sample. This technique, known as ABPP-MudPIT (multidimensional protein identification technology) is especially useful for profiling inhibitor selectivity as the potency of an inhibitor can be tested against hundreds of targets simultaneously.^{[citation needed]}

ABPP were first reported in the 1990s in the study of proteases.^[6][7]

See also

• Mass spectrometry
• Proteomics
• Related inhibitors MAFP and DIFP
• Chemoproteomics