Sunlight is essential for all life, and living organisms have evolved to sense and respond to light. Dronpa is a protein “light switch” that can be turned on and off by light. A team of scientists led by Peter Tonge, a Professor in the Department of Chemistry at Stony Brook University, has discovered a way to use infrared spectroscopy to determine for the first time structure changes that occur in Dronpa during the transition from the dark (off) state to the light (on) state. Their findings are reported in a paper published early online in Nature Chemistry.