Fluorescein energy transfer from coumarin

Aminomethylcoumarin derivatives possess intense fluorescent properties within the blue region of the visible spectrum. Their emission range is sufficiently removed from other common fluorophores that they are excellent choices for double-labeling techniques. In fact, coumarin fluorescent probes are very good donors for excited-state energy transfer to fluoresceins. 

A FRET-based reporter gene assay that is now commercially available from Panvera was described by Zlokarneik and co-workers [109]. The assay uses a membrane-permeable substrate (CCE2, a coumarin-fluorescein derivative) for the reporter protein j3-lactamase. By hydrolyzing the substrate, the enzyme disrupts the intramolecular resonance energy transfer between the coumarin and the fluorescein, which changes the fluorescence emission from green at 520 run to blue at... 

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