A Guide to Activity-based Probes

To characterize a proteome, one needs to know not only the types and quantities of proteins, but also what they're doing. Quantitative proteomics methods such as two-dimensional electrophoresis (2DE) don't reveal activity. And many proteomics tools miss low-abundance proteins. Enter activity-based proteomics, which sends specially-designed molecular probes armed with reactive warheads to seek out and tag enzyme molecules. Capable of working in cell homogenates and sometimes even in live animals, these activity-based probes (ABPs) form irreversible covalent bonds with the desired active protein target. The target then becomes much easier to enrich and analyze. "The huge advantage is that you can simplify a very complex proteome," says Ruth Birner-Grnberger from Graz University of Technology in Austria, who has developed probes for studying key active enzymes in the lipid metabolism. "You only label the enzymes you're really interested in."