We all learned about photosynthesis back in middle school This week, researchers from Arizona State University revealed the water-splitting stages of photosynthesis in insane detail. Researchers described the results in a study called Serial time-resolved crystallography of photosystem II using a femtosecond X-ray laser. The study was published in the latest issue of the journal Nature.

“This study is the first step towards our ultimate goal of unraveling the secrets of water splitting and obtaining molecular movies of biomolecules,” said Petra Fromme, the study’s senior author, in a press release.

Let’s take a deeper look into the water-splitting stage of photosynthesis. This process is essential to life across the Earth as it represents the greatest source of the atmosphere’s oxygen.

Photosynthesis takes place in a unique area that comprises four manganese atoms and one single calcium atom. These atoms for a cluster known as the oxygen-evolving complex (OEC). This complex oxidizes water molecules.

The OEC structure cycles through five states (S0 to S4) and controls the light dependent portion of the water-splitting reaction.


Researchers have tried to get a better look at the OEC in the past, but would come up with mixed results. High-intensity X-rays impacted the manganese atoms in such a way that it altered the OEC structure.

The researchers from Arizona State University got around this issue by using the Linac Coherent Light Source (LCLS). Basically, the world’s most powerful X-ray laser.

Researchers were able to capture images of the photosystem II nanocrystals just before they exploded from the laser. What did they find? The water-splitting stages led to an overall structure change. The OEC elongated to accommodate molecules of the water and the changes to the protein environment.

Fromme described the changes they witnessed a bit more in the press release.

“We were surprised by the large conformational changes we could witness… Actually, the changes are so large that there is an overall structure change, which even changes the dimensions of the unit cell, the smallest building block in a crystal.”

This discovery could prove incredibly useful to scientists developing an “artificial leaf,” which would be able to produce energy and oxygen.


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