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Research Team Develops Novel Fluorescent Probe Library

Protein glutathione S-transferase (GST) used as  target for a proof-of-concept study

Probe libraryProbe library yielded GST-specific CCTO probes, which change color from yellow to cyan when they bind.Image courtesy of the University of Electro-Communications, TokyoThe ability to visualize, detect and track specific proteins is highly desirable for scientists working in a variety of disciplines, such as disease diagnostics and cell biology. To this end, ‘fluorogenic probes’ are often used–molecular dyes which bind to target molecules and fluoresce in response to the surrounding microenvironment. Some probes hold the ability to change color and ‘turn on’ (known as CCTO), emitting a much brighter light upon recognition of the target molecule.

There are some issues with the use of fluorogenic probes. For example, adding a fluorescent molecule (or fluorophore) into a peptide or ligand capable of binding to the target can sometimes inhibit correct binding, causing a weak link. Moreover, current fluorogenic probes are built only for certain specific protein-ligand pairs, and the search is on for a way to find probes suitable for a wider range of targets.

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Now, Masumi Taki and co-workers at the University of Electro-Communications in Tokyo, together with co-workers in Japan and the USA, have synthesized a diverse fluorogenic probe library using a form of the fluorescent dye Prodan and phage display technology based on bacteriophage T7.

The team selected the protein glutathione S-transferase (GST) as their target for a proof-of-concept study. Their probe library yielded GST-specific CCTO probes, which changed color upon binding from yellow to cyan. The intensity of the cyan fluorescence also increased upon target recognition. The color-change ability is most highly prized, because an obvious signal such as this can result in less ambiguous read-outs when searching for specific targets.

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Further trials using the new probe library will help Taki and his team determine its advantages and limitations.