Energy differences behind green fluorescent protein's glow in jellyfish skirts and biological studies
Credited with revolutionizing scientific studies, green fluorescent proteins or GFPs let scientists track molecules in complex reactions inside cells. Found in jellyfish and other marine animals, GFP glows green when hit with light. For all the interest in GFP, the exact changes in its energy and structure as it winks on and off were not clearly understood, so scientists at Pacific Northwest National Laboratory (PNNL) and their collaborators conducted an exacting series of measurements. For the first time, they determined—unequivocally—that the energy level of the excited state of the molecule or chromophore anion solely responsible for the fluorescence after light is absorbed lies below the energy level of the neutral form. Their results unravel key molecular-level energetic conditions that explain the extremely high fluorescence efficiency of GFPs.