A femtosecond x-ray pulse from an x-ray free electron laser intersecting a droplet that contains photosystem II crystals, the protein extracted and crystallized from cyanobacteria.SLAC NATIONAL ACCELERATOR LABORATORYBehind photosynthesis, there’s photosystem II. An essential protein complex found in plants, algae, and cyanobacteria, photosystem II seizes sunlight to cleave water into charged particles (which reduce carbon dioxide) and release oxygen into the air. Now, a November 21 study in Nature depicts the inner workings of photosystem II, with a battery of high-resolution 3-D images captured by the X-ray free-electron laser at the Linac Coherent Light Source (LCLS) at Stanford University.
“We have been trying for decades to understand how plants split water into oxygen, protons, and electrons,” said coauthor Vittal Yachandra of the Lawrence Berkeley National Laboratory, in a press release. “Understanding how nature accomplishes this difficult reaction so easily is important for developing a cost-effective method for solar-based water-splitting, which is essential for artificial photosynthesis and renewable energy.”
Most of this action takes place in the thylakoid membrane, a compartment within chloroplasts that houses light-dependent, photosynthetic reactions. Until now, scientists based most of their conclusions on cryo-imaging, or X-ray techniques that shatter the chloroplast. This new approach uses rapid laser pulses—to the tune of 40 femtoseconds per pulse—that capture the data before the sample is destroyed. “The stages of photosystem II do not proceed ...
