Ultrafast excited-state dynamics of the green fluroscent protein

In this work, we have investigated, by spectrally time-resolved pump-probe spectroscopy, the excited-state dynamics of the uv mutant of the green fluorescent protein (GFPuv). The gain dynamics of GFPuv is characterized by a mono-exponential behaviour and can be described by a simple model involving a photo-conversion between two form of the GFPuv chromophore. In order to obtain more information about the role played by the interaction between the chromophore and the proteic cage, we have performed spectrally time-resolved femtosecond experiment on synthetic GFP chromophore analogue. This study allows us to evidence the importance of chromophore-proteic cage interaction in the gain dynamics. Finally we investigated the excited-state dynamics of GFPuv fused with single chain antibody fragment (scFv). The subjacent idea is to use the dynamical photo-physical properties of GFPuv fused with scFv as folding reporter. By taking two scFvs, one is a well-folded antibody and one is a misfolded antibody, we have evidenced that the observed pump probe differential transmission spectra are affected by the presence of the misfolded antibody. This result shows that the tertiary structure of the protein can be modified by the presence of a misfolded scFv linked to the GFPuv.