https://www.sciencedaily.com/releases/2020/01/200114104037.htm

Now a team headed by Dr. Ulrich Schade (HZB) and Dr. Eglof Ritter (Humboldt-Universität zu Berlin) at the IRIS beamline of BESSY II has developed a new instrument that can detect these kinds of very fast and/or irreversible reactions with a single measurement. The time resolution is a few microseconds. The instrument, a Féry spectrometer, uses a highly sensitive detector known as a focal-plane detector array and special optics to make optimal use of the brilliant infrared radiation of the BESSY II synchrotron source. The team used this device to observe activation of rhodopsin under near-in vivo conditions for the first time.

"We used rhodopsin because it irreversibly decays after being excited by light and is therefore a real acid test for the system," explains Ritter, first author of the study. Rhodopsin is a protein molecule that acts as a receptor and is the vision pigment found in the rods of the eye's retina. Even single photons can activate rhodopsin -- enabling the eye to perceive extremely low levels of light. Moreover, rhodopsin is the common element in a class of receptors with hundreds of members that are responsible for olfaction, taste, pressure sensation, hormone reception, etc. -- all of which function in a similar manner.