Physics

New Observation Of Photosynthesis Reveals How Much We Don't Know

An international team of scientists watched the minute details of how plants make oxygen. By using the sophisticated SLAC X-ray laser, they were able to accurately observe how photosynthesis happens at room temperature, and it doesn’t happen like we thought.

The team was previously only able to observe photosynthesis in frozen samples and at low luminosity, which doesn’t produce a high-fidelity picture of photosynthesis. The latest laser upgrade, the Linac Coherent Light Source (LCLS), has allowed researchers to actually see the photosynthetic splitting of water – an observation that could open up a world of technical applications.

“The eventual goal is to emulate what photosynthesis has been doing for about three billion years. This has been a research challenge for decades,” said Junko Yano, principal investigator and senior scientist at Lawrence Berkeley National Laboratory, in a statement. “We now have the right tool, the femtosecond X-ray laser pulses created at LCLS, that allows us to observe the water-splitting reaction as it happens, in real time, and as it happens in nature.”

The research, published in Nature, provides a look at the photosystem II protein, the catalyst that helps release oxygen from water. The protein has a metallic core made of four manganese atoms and one calcium atom. Using energy from light, an oxygen molecule is formed from two molecules of water.

While scientists have long known the crucial role played by manganese in shuffling electrons and breaking the bonds between hydrogen and oxygen, the data doesn’t support the two main theories that have been proposed to explain photosynthesis.

“The chemistry is so unusual,” co-principal investigator and senior scientist Vittal Yachandra at Berkeley Lab said. “Learning how exactly this water-splitting process works will be a breakthrough in our understanding, and it can help in the development of solar fuels and renewable energy.”

While the collected data is incredible, it is still not enough to produce a complete picture of photosynthesis. More observations with the LCLS will hopefully provide more snapshots of the reaction and help clarify what the scientists are missing.

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