Image: Kevin Redding, Arizona State University
It is one of the mysteries that makes life on earth possible: plants can grab energy out of sunlight and convert it into chemical energy. This energy works its way up the food chain. Without it, we could not exist. With a better understanding of how it works, perhaps we could develop ways to use energy from the sun efficiently enough to replace the role of fossil fuels in the modern world.
But we don't know how it works. And when you learn what is required to figure it out, you too will be amazed at the newest step scientists have taken towards unlocking the mysteries of photosyntheis.It took an international team of scientists over two years of laboratory work to create samples of sufficient purity to use for their research. The goal: create samples of mutants of a single-celled green algae (Chlamydomonas reinhardtii) which used one of two possible pathways preferentially. The team exposed their algal mutants to laser pulses lasting a mere 60 millionths or one billionth of a second. This means they were working on the kind of time scale in which an atom can only wiggle back and forth in its location maybe a dozen times.
This exacting method allowed the scientists to see what none had seen before: the moment when electromagnetic energy from the sun is converted into chemical energy for building sugars or carbohydrates. And they learned something that may significantly influence the design approach for artificial photosynthesis devices. The light-triggered reaction can start independently on one of two different branches in the photosynthesis complex. The system uses the two branches in parallel to increase the overall efficiency of charge transfer.
The work required a cooperative effort of a team led by Kevin Redding, at Arizona State University, and a team at the Max Planck Institute (MPI) in Mülheim on the Ruhr in Germany led by Alfred Holzwarth. The Arizona lab developed the mutant algae and the MPI team conducted the laser studies. Their work focuses on one of two photosynthesis complexes, known as photosystem I (PSI; the other is photosystem II, PSII). Their paper, titled "Independent initiation of primary electron transfer in the two branches of the photosystem I reaction center," appears in this week's online Early Edition of the Proceedings of the National Academy of Sciences (PNAS).
More Science of Photosynthesis:
Scientists Build A Better Leaf?
Improve Solar Technology -Design a Biomimic of Photosynthesis
Carbon Nanotubes Could Make Artificial Photosynthesis Possible
Key Green Algal Genome Provides Insights into Carbon Capture, Better Biofuels Production