Surprising Twist To Photosynthesis: Scientists Swap Key Metal Necessary For Turning Sunlight Into Chemical Energy

Description

Caption: The reactions that convert light to chemical energy happen in a millionth of a millionth of a second, which makes experimental observation extremely challenging. A premier ultrafast laser spectroscopic detection system established at the Biodesign Institute, with the sponsorship of the National Science Foundation, acts like a high-speed motion picture camera. It splits the light spectrum into infinitesimally discrete slivers, allowing the group to capture vast numbers of ultrafast frames from the components of these exceedingly rapid reactions. These frames are then mathematically assembled, allowing the group to make a figurative "movie" of the energy transfer events of photosynthesis. (Credit: Arizona State University Biodesign Institute)

ScienceDaily (May 23, 2009) — Photosynthesis is a remarkable biological process that supports life on earth. Plants and photosynthetic microbes do so by harvesting light to produce their food, and in the process, also provide vital oxygen for animals and people.

Now, a large, international collaboration between Arizona State University, the University of California San Diego and the University of British Columbia, has come up with a surprising twist to photosynthesis by swapping a key metal necessary for turning sunlight into chemical energy.

The team, which includes: ASU scientists Su Lin, Neal Woodbury, Aaron Tufts and James P. Allen; UBC colleagues J. Thomas Beatty, Paul R. Jaschke, Federico I. Rosell and A. Grant Mauk; Mark Paddock, UCSD; Haiyu Wang, Jilin University, China, described their findings in the May 11 early online edition of the Proceedings of the National Academy of Sciences .

In the heart of every green leaf are pigments called chlorophyll, which not only give most plants their color, but also along with the yellow and orange carotenoid pigments, are key molecules that harvest light across the spectrum.

In all plant chlorophylls, only one particular metal, magnesium, is held tightly within the molecule's center.

During photosynthesis, plants have two photosystems that work in tandem: photosystem I and photosystem II. To peer at the inner workings of photosynthesis, the team used a hardy, well-studied, photosynthetic bacterium called Rhodobacter sphaeroides. An organism similar to this purple bacterium was likely one of the earliest photosynthetic bacteria to evolve. The purple bacteria possess a simplified system similar to photosystem II.

The center stage of photosynthesis is the reaction center, where light energy is funneled into specialized chlorophyll binding proteins. The research team had previously demonstrated that …

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http://www.sciencedaily.com/releases/2009/05/090511180653.htm