Fluorescence Resonance Energy Transfer spectroscopy



A bit of theory...



What is FRET?


"Resonance energy transfer is the radiationless transmission of an energy quantum from its site of absorption to the site of its utilization in the molecule, or system of molecules, by resonance interaction between chromophores, over distances considerably greater than interatomic, without conversion to thermal energy, and without the donor and acceptor coming into kinetic collision. The donor is the dye that initially absorbs the energy, and the acceptor is the chromophore to which the energy is subsequently transferred". (from: Van Der Meer, B.W., Coker, G.III, and Chen, S.-Y. (1994) Resonance Energy Transfer Theory and Data, VCH, New York).

Back to Top 


What do you need?


 

 

Back to Top 


The equations...


 

Once the conditions to observe FRET are met, and the donor probe is excited at the appropriate wavelength, decay as donor fluorescence and energy transfer to the acceptor will compete for the decay of the excitation energy and can be described by the following scheme:  

where D refers to the donor probe and A to the acceptor probe (see figure 1), Kd and Ka are the radiative decays of the donor in the absence of the acceptor and of the acceptor, respectively. Kt is the rate of energy transfer(radiationless), hve, hvd and hva are the photon energies of the donor excitation, of the donor fluorescence and of the acceptor fluorescence. Kdi and Kai are radiationless decay constants. (from Van der Meer et al., 1994)

 

Back to Top 


The upside...


 

 

Back to Top 


...and the downside


 

 

Back to Top 


Back to Home Page
If you have any comments or suggestions to improve this page please email me at pierre.moens@ibgc.u-bordeaux2.fr