TR-FRET

TR-FRET assays are very robust (limited sensitivity to several types of assay interference) and are easily miniaturized. Robustness, the ability to automate and miniaturize are features that are highly attractive in a screening laboratory. A 337 nm laser is essential as the excitation source for the best performance with these assays, providing speed and excellent sensitivity. Like TRF, TR-FRET assays use lanthanides, which have a longer post-excitation lifetime than standard fluorescence dyes, usually in the microsecond to millisecond range. When excited by a pulsed light source such as a 337 nm laser, followed by a short wait time, the short-lived background fluorescence diminishes so a “cleaner” fluorescence signal is detected, with a much lower background than conventional fluorescent dyes provide. use lanthanide chelates (e.g. Europium) or cryptates. These compounds have a longer post-excitation lifetime than standard fluorescence dyes. Usually in the microsecond to millisecond range. When excited by a pulsed light source such as a xenon flash lamp, then wait a few microseconds, the short-lived background fluorescence diminishes so a “cleaner” fluorescence signal is detected, with a much lower background than conventional fluorescent dyes provide.

Homogeneous FRET assays called HTRF® assays are a trademarked assay platform (Cisbio) based on TR-FRET.

Assay principal for AlphaScreen® SureFire®  STAT3 assay
 

TR-FRET assay principle

  • When excited, the TR donor emits light over a few milliseconds.

  • When excited directly, the acceptor emits light over a few nanoseconds.

  • When FRET occurs, the energy transfer occurs over a few milliseconds, thus the emission of the acceptor occurs in the same time-frame.

 

TR-FRET is available in:

 

 

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