• photoswitchable fluorescent proteins
• fluorescent proteins
• super-resolution fluorescence microscopy

The major goal of this thesis is the investigation of the photophysical and photochemical properties of two new mutant fluorescent proteins from the Aequorea jellyfish family, namely wQL and EYQ1L.
Our target was actually to assess whether the Q69L mutation could positively cooperate with E222Q to improve the photoswitching properties as compared to E222Q alone. In this context, we always compared the mutation effect on each couple, the green one (wQ/wQL) and the yellow one (EYQ1/EYQ1L).
All our experiments highlight the peculiar properties of wQL as RSFP, namely high bright/dark contrast ratio, high off-switching quantum yield and strong resistance to photobleaching.
The high performances of the mutant wQL in terms of photoswitching opens the way to several application in super-resolution fluroescence microscopy with possibly strong implications in terms of biological results.