Proton relay reaction in green fluorescent protein (GFP): Polarization-resolved ultrafast vibrational spectroscopy of isotopically edited GFP.

The complex transient vibrational spectra of wild type (wt) GFP have been assigned through polarization anisotropy measurements on isotopically edited proteins. Protein chromophore interactions modify considerably the vibrational structure, compared to the model chromophore in solution. An excited-state vibrational mode yields information on excited-state electronic structure.