Excited state dynamics in the green fluorescent protein

The photophysical properties of the wild type green fluorescent protein (wtGFP), the isolated GFP chromophore in solution, and a number of GFP mutants are described. The mechanism of the very efficient radiationless decay of the isolated chromophore is discussed in the light of experimental measurements and theoretical calculations. The dramatic switch in photophysics, from radiationless decay dominated to proton transfer dominated, between the isolated chromophore and wtGFP is illustrated and discussed. The excited state dynamics and their manipulation through mutagenesis are described. The potential for utilizing GFP as a model system for studying the dynamics of proton transfer reactions in proteins, including low barrier hydrogen bonds and proton transport on proton wires, is discussed.