FörsterResonanzenergietransfer

Förster Resonance Energy Transfer, often abbreviated as FRET, is a non-radiative energy transfer mechanism between two light-sensitive molecules called chromophores. It occurs when a donor fluorophore in its excited electronic state transfers energy to an acceptor chromophore through long-range dipole-dipole interactions. This transfer is highly dependent on the distance between the donor and acceptor, typically occurring over distances of 1 to 10 nanometers. The efficiency of FRET decreases with the sixth power of the distance, making it a sensitive probe for molecular proximity.

The process requires that the emission spectrum of the donor overlaps significantly with the absorption spectrum of the acceptor. Additionally, the transition dipole moments of both chromophores must be favorably oriented. FRET is a photophysical process and does not involve the emission and reabsorption of a photon. Instead, the energy is directly transferred from the excited donor to the ground state acceptor, which then becomes excited.

FRET finds widespread applications in various scientific fields, particularly in molecular biology and biophysics. It is commonly used to study protein-protein interactions, conformational changes in biomolecules, and the dynamics of molecular assemblies. By labeling molecules of interest with FRET pairs, researchers can monitor their interactions or structural alterations in real-time. The development of fluorescent proteins that exhibit FRET properties has further revolutionized its use in live-cell imaging and in vivo studies.