The Reach construct

The FRET (Förster Resonance Energy Transfer) System

Förster resonance energy transfer (FRET), sometimes also called fluorescence resonance energy transfer, is a physical process of energy transfer named after the German physical chemist Theodor Förster. In FRET, the energy of a donor chromophore, whose electrons are in an excited state, is transferred to a second chromophore, the acceptor. The energy is transferred without radiation and is therefore not exchanged via emission and absorption of photons. In biochemistry and cell biology, fluorescent dyes, which interact via FRET, are applied as "optical nano metering rules", because the intensity is depend on the spacing between donor and acceptor, and can be observed up to distances of 10 nm. This way, protein-protein interactions and conformational changes of a variety of tagged biomolecules can be observed.

However, fluorescence is not an essential requirement for FRET. This type of energy transfer can also be obersved between donors that are capable of other forms of radiation, such as phosphorescence, bioluminescence or chemiluminescence, and fit acceptors. Acceptor chromophores do not necessarily emit the energy in form of light, and can lead to quenching. Thus, this kind of acceptors are also referred to as dark quenchers. In our project, we use a FRET system, namely our Reach construct.

The Reach proteins as quenchers for GFP

Producing a GFP_Reach Fusion Protein

Cutting the fusion protein with the TEV Protease

A Fluorescence answer faster than expression