Infinite average lifetime of an unstable bright state in the green fluorescent protein

The time evolution of the fluorescence intensity emitted by well-defined ensembles of Green Fluorescent Proteins has been studied by using a standard confocal microscope. In contrast with previous results obtained in single molecule experiments, the photo-bleaching of the ensemble is well described by a model based on Levy statistics. Moreover, this simple theoretical model allows us to obtain information about the energy-scales involved in the aging process.