DRAMATIC REDUCTION IN FLUORESCENCE QUANTUM YIELD IN MUTANTS OF GREEN-FLUORESCENT-PROTEIN DUE TO FAST INTERNAL-CONVERSION

Steady-state absorption and fluorescence excitation spectra together w ith ps-fluorescence and fs-absorption measurements have identified an important relaxation channel of excited states in Green Fluorescent Pr otein (GFP). GFP derivatives with (1) shortened lifetimes of the proto nated chromophore RH state and deprotonated chromophore R-* state, an d (2) rapid recovery of the RH or R- ground state have been isolated a nd characterized. These shortened excited state lifetimes and fast gro und state recovery are interpreted in terms of internal conversion ind uced by torsional motion within the chromophore. (C) 1998 Elsevier Sci ence B.V. All rights reserved.