Scientists have accidentally discovered that photosynthesis, one of the best-studied chemical processes in nature, may not work as we thought.
photosynthesis A process by which plants, algae, and some bacteria convert carbon dioxide and water into oxygen and sugars for use as energy. To do this, organisms use sunlight to oxidize water or extract electrons from it. Reduces or gives electrons to carbon dioxide molecules. These chemical reactions require a photosystem—a protein complex containing chlorophyll, the pigment that absorbs light and gives plant leaves and algae their green color—to transfer electrons between different molecules.
In a new study published March 22 in the journal Nature (opens in new tab), researchers used a new technique known as ultrafast transient absorption spectroscopy to study for the first time how photosynthesis works on the timescale of one trillionth of a second (0.000000000000001 seconds). The team was initially trying to understand how quinones, ring-shaped molecules that can steal electrons during chemical processes, affect photosynthesis. discovered that more electrons may be released from the photosystem during photosynthesis than previously believed possible.
“We thought we were just using new techniques to confirm what we already knew,” study co-author Jenny Chan (opens in new tab)A biochemist specializing in photosynthesis at the University of Cambridge, UK, said: statement (opens in new tab)“Instead, we discovered an entirely new pathway, further opening up the black box of photosynthesis.”
Related: New ‘artificial’ photosynthesis is 10 times more efficient than previous attempts
Photosynthesis uses two photosystems, photosystem I (PSI) and photosystem II (PSII). PSII donates electrons to PSI primarily by acquiring electrons from water molecules. PSI releases more electrons, then releases them, through a series of complex steps, and finally given to carbon dioxide to produce sugars.
Previous studies have suggested that the protein scaffolds of PSI and PSII are very thick, which helps to trap electrons inside before they are passed where they are needed. However, a new ultrafast spectroscopy method reveals that protein scaffolds are more ‘leaky’ than expected, allowing some electrons to escape from the photosystem shortly after light is absorbed by chlorophyll within the system. became. These electrons can therefore reach their destination faster than expected.
“The new electron transfer pathways discovered here are absolutely amazing,” said Zhang. “We didn’t know as much about photosynthesis as we thought.”
Electron leakage was observed both in isolated photosystems and in ‘living’ photosystems within cyanobacteria.
In addition to rewriting what we know about photosynthesis, this discovery opens new avenues for future research and biotechnology applications. The team believes that by “hacking” photosynthesis to release more of these electrons in the early stages, the process becomes much more efficient, producing plants that are more tolerant of sunlight, or artificially. We believe it can be replicated to create a renewable energy source to aid in combat. Climate change, according to the statement. However, more research is needed before this can be realized.
“Many scientists have tried to extract electrons from the early stages of photosynthesis, but they said it was impossible because the energy is buried in the protein scaffold,” Zhang said. “The fact that you can [potentially] Stealing them earlier in the process would be amazing. “
