Fluorescence spectroscopy is a versatile technique which allows to analyze, at steady-state or in real time, the variations of the environment of fluorescent probes, either intrinsic (for instance tryptophans in the case of proteins) or extrinsic (synthetic fluorophores). This technology can notably be applied to the study of the conformational stability of macromolecules, the characterization of molecular interactions and the quantification of enzymatic activities. The PFBMI has a “stopped-flow” instrument (KinetAsyst SF61-DX2, TgK Scientific), allowing to determine the properties of fast reactions with a time resolution of a fraction of a millisecond.