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Fast assay for active enzymes
A high-throughput general assay to detect proteins with specific types of enzymatic activity has been developed by chemistry assistant professor Virginia W. Cornish and colleagues at Columbia University [Proc. Natl. Acad. Sci. USA, 99, 16537 (2002)]. In earlier work, the researchers constructed small molecules consisting of two different ligands connected by a linker. Each ligand binds tightly to a receptor protein that can be fused to other proteins involved in gene activation. When both ligands bind to their proteins, a reporter gene is activated. Now, the chemists have replaced the linker of their earlier molecules with a molecule that serves as the substrate for a particular class of enzyme. In their proof-of-principle experiment, the linker is a cephalosporin molecule. In the presence of a cephalosporin-hydrolyzing enzyme, the enzyme cleaves the linkage and the reporter gene is turned off. Other linkers could be specific for other types of enzymes, including those that form--rather than cleave--bonds, the chemists note. The work "represents a first step in creating generalized detectors of enzyme activities in cells," according to an accompanying commentary
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