Explain how FRET works Why does the first molecule fluoresce

Explain how FRET works. Why does the first molecule fluoresce? Why does this fluorescence cause the second molecule to fluoresce? What does FRET measure?

Solution

FRET stands for fluorescence resonance energy transfer. It is a mechanism of transfer of energy between two light sensitive molecules known as chromophore. The primary chromophore is first exited with a particular wavelength, after absorption primary chromophore emits light with lower wavelength which is absorbed by secondary chromophore. The primary chromphore act as fluorescence donor and secondary chromophore act as acceptor.

FRET technique is used to estimate the distance between sites on a macromolecule (eg: proteins) through microscopic techniques. Here the distance between doner and acceptor is measured to obtain structural information.