Excited state structural evolution in fluorescent proteins and their model chromophores

Abstract

The discovery of green fluorescent protein (GFP) has revolutionized molecular and cellular biology. Photocycle in wt-GFP involves generation of a bright fluorescent deprotonated chromophore from feebly fluorescent protonated form via excited-state proton transfer (ESPT). The chromophore loses its fluorescence outside the protein matrix due to ultrafast structural changes (ring twisting motion) during ESPT. To identify the key vibrational modes leading to such structural changes, we recently demonstrated how a systematic analysis of spectral data from non-resonant/resonant impulsive excitation followed by spectral dispersion disentangles vibrations arising in ground/excited electronic states of solute and solvent.