Ultrafast gain dynamics of the green fluorescent protein

We investigated the excited state dynamics of the uv mutant of the green fluorescent protein (GFPuv) using spectrally resolved femtosecond pump–probe spectroscopy. The gain dynamics of GFPuv is characterized by a ‘slow’ picosecond mono-exponential growth contrary to the wild type (GFPwt) where ultrafast components have been previously reported. As GFPwt and GFPuv share the same chromophore, this difference can be attributed to an intrinsic improved homogeneity of the GFPuv sample. The study of a synthetic GFP chromophore allows us to confirm the key-role played by the interactions chromophore–proteic cage in GFP photophysics.