Dramatic reduction in fluorescence quantum yield in mutants of Green Fluorescent Protein due to fast internal conversion Original Research Article

Steady-state absorption and fluorescence excitation spectra together with ps-fluorescence and fs-absorption measurements have identified an important relaxation channel of excited states in Green Fluorescent Protein (GFP). GFP derivatives with (1) shortened lifetimes of the protonated chromophore RH* state and deprotonated chromophore R−* state, and (2) rapid recovery of the RH or R− ground state have been isolated and characterized. These shortened excited state lifetimes and fast ground state recovery are interpreted in terms of internal conversion induced by torsional motion within the chromophore.