Grab some popcorn: Lawrence Berkeley National Laboratory (Berkeley Lab) scientists have succeeded in capturing a more detailed picture than ever of the steps in the reaction mechanisms in photosynthesis, the process by which plants use sunlight to split water and produce oxygen while making the carbohydrates that sustain life on Earth.

“It’s like a molecular movie,” said Vittal Yachandra, one of the lead scientists on the study. “We’re collecting more and more of these snapshots. The idea is eventually to have a continuous story of how water is split into oxygen, and how plants do that using sunlight.”

The study was published in Nature today and included an international team of researchers from Berkeley Lab, SLAC National Accelerator Laboratory, Humboldt University of Germany, Umeå University and Uppsala University of Sweden, and the Diamond Light Source in the UK.

Berkeley Lab researchers (front row, from left) Iris Young, Sheraz Gul, Ruchira Chatterjee, Junko Yano, Vittal Yachandra, (back, from left) Nigel Moriarty, Jan Kern, Aaron Brewster, and Nicholas Sauter have captured the most complete images of photosynthesis in action. (Credit: Marilyn Chung/Berkeley Lab)

“We hope a better understanding of photosynthesis and the guiding principles we learn from these studies can then be applied to develop artificial photosynthetic systems, which is a way to produce fuels from sunlight, water, and carbon dioxide,” said Junko Yano, also one of the lead scientists.

The team used SLAC’s Linac Coherent Light Source (LCLS) X-ray laser to capture atomic-scale images of Photosystem II, a protein complex found in plants, algae, and cyanobacteria responsible for splitting water, in action. Berkeley Lab’s Advanced Light Source (ALS), a particle accelerator that generates bright beams of X-ray light, was essential for optimizing the crystals for the X-ray laser experiments.

Two years ago, the scientists – led by Yano, Jan Kern, and Yachandra in Berkeley Lab’s Biosciences Area – forged a technique to capture two steps of the water-splitting cycle. In the latest study they used the same technique, which took years to develop, to capture six images in the process with more detail than ever before – three times more data in each snapshot, to be precise. Berkeley Lab Biosciences researchers Nicholas Sauter and Paul Adams, also co-authors of the paper, developed critical software and algorithms that provided a completely new way of analyzing the data from the X-ray laser.

First frames of a movie of the water oxidation reaction in nature: Light-induced changes observed at the Mn cluster of photosystem II as it goes through its catalytic cycle. (Credit: Berkeley Lab)

“Previously the picture was more blurred and it was difficult to see details,” said Kern, lead author of the new study. “Now we have a sharper picture for these six steps. We estimate that if we get another five or 10 snapshots along the last step in the reaction, that will really tell us what is going on in detail.”

Added Yano: “In 2016 we showed we could see structural details that are useful. Now we have several frames of the movie where we can see the details of the chemistry taking place in real time.”

LCLS and ALS are Department of Energy Office of Science user facilities.

Click here to read SLAC’s news release on this research.

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