Featured Research

from universities, journals, and other organizations

New Research Sheds Light On Photosynthesis

Date:
November 28, 2006
Source:
Max-Planck-Gesellschaft
Summary:
An international group of researchers working with a Max Planck scientist determines the arrangement of atoms in the manganese cluster of photosystem II.

The photosystem II crystal (centre of image) is smaller than the head of a pin. In order to position it better, the scientists irradiate it with green light. Helium flowing in from above cools it to minus 260 degrees Celsius. The highly-pulsed and polarised X-ray hits the sample from bottom right. The tip of the EXAFS detector, which is equipped with 30 elements, protrudes from the left edge.
Credit: Image : Johannes Messinger/ MPI for Bioinorganic Chemistry

Coal, oil or natural gas: all fossil fuels contain the energy of sunlight, stored with the aid of photosynthesis in energy-rich chemical compounds. A researcher at the Max Planck Institute for Bioinorganic Chemistry in Mόlheim on the Ruhr working with colleagues from the Technical University in Berlin, the Free University in Berlin and the Lawrence Berkeley National Laboratory has shed light on an important detail in this process. The scientists have determined the structure of the complex in photosystem II, in which water is split with the energy of sunlight. This creates, in addition to molecular oxygen, protons and electrons which in principle can be combined to create hydrogen. If it were possible to copy this process, an inexhaustible source of carbon dioxide-free energy would become available (Science, November 3, 2006).

Artificial photosynthesis could provide the energy source of the future - hydrogen. To accomplish this, however, researchers must fully understand how plants and photosynthetic microorganisms split water with the energy of sunlight - only then would they be able to copy the process one day. Together with his colleagues, Dr. Johannes Messinger has now determined the precise structure of the part of the cluster containing manganese in which water is split into its component parts. Up to now it has been technically impossible to efficiently recreate this crucial step.

There are four manganese, one calcium and at least five oxygen atoms linked together in the complete cluster. "The secret is in their geometric arrangement. We discussed at least 18 models for the arrangement of just the manganese and oxygen atoms," said Johannes Messinger, senior research scientist at the Max Planck Institute in Mόlheim. With their experimental and theoretical work, the scientists have put an end for now to speculation about the correct geometrical arrangement. According to their findings, the cluster is constructed of three linked rhombi. Two of the manganese and oxygen atom rhombi share an edge, so that both one manganese and one oxygen atom have three bond partners. Another manganese atom is even surrounded by four bridging oxygen atoms as the third rhombus is attached to it. "We have also calculated the distances between the individual manganese atoms," said Johannes Messinger. Previously, scientists knew that the manganese atoms were not all separated by the same distance. The international team of researchers has now found out which manganese atoms are closer and which are further apart.

Messinger and his colleagues have derived these findings from experiments (particularly those with EXAFS measurements) and from theoretical considerations. They used a computer to compare all the theoretically possible atom arrangements with the results of the experiments and were successful. "In the end there was only one arrangement for the four manganese atoms with the bridging oxygen atoms," said Messinger. "This takes us a crucial step further." There remain only two details to be cleared up: the new findings allow for three possibilities for the orientation of the cluster in the protein of photo system II, which gives four possible positions for the calcium.

The scientists in the international group developed the EXAFS (Extended X-ray Absorption Fine Structure) measurement system further for their investigations. This determines exactly the types of atoms and the distance between them and provided them with an insight that is denied crystallographers. In the past, when crystallographers tried to reveal the blueprint for the manganese cluster using X-ray structure analysis, the necessarily high doses of radiation destroyed the structure of the cluster [Yano et.al. Proceedings of the National Academy of Sciences of the USA, 102 (2005) 12047-12052]. To protect the cluster from a similar fate, the scientists used the low radiation doses of the EXAFS method and replaced the crystal repeatedly after short periods of measuring in the synchrotron beam.

"We now have a structural basis with which to understand the different stages of reactions in the process that uses sunlight to split water," says Messinger. "This is an important step towards developing artificial catalysts for regenerative hydrogen production."


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Cite This Page:

Max-Planck-Gesellschaft. "New Research Sheds Light On Photosynthesis." ScienceDaily. ScienceDaily, 28 November 2006. <www.sciencedaily.com/releases/2006/11/061128093235.htm>.
Max-Planck-Gesellschaft. (2006, November 28). New Research Sheds Light On Photosynthesis. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2006/11/061128093235.htm
Max-Planck-Gesellschaft. "New Research Sheds Light On Photosynthesis." ScienceDaily. www.sciencedaily.com/releases/2006/11/061128093235.htm (accessed July 31, 2014).

Share This




More Matter & Energy News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Britain Testing Driverless Cars on Roadways

Britain Testing Driverless Cars on Roadways

AP (July 30, 2014) — British officials said on Wednesday that driverless cars will be tested on roads in as many as three cities in a trial program set to begin in January. Officials said the tests will last up to three years. (July 30) Video provided by AP
Powered by NewsLook.com
Amid Drought, UCLA Sees Only Water

Amid Drought, UCLA Sees Only Water

AP (July 30, 2014) — A ruptured 93-year-old water main left the UCLA campus awash in 8 million gallons of water in the middle of California's worst drought in decades. (July 30) Video provided by AP
Powered by NewsLook.com
Smartphone Powered Paper Plane Debuts at Airshow

Smartphone Powered Paper Plane Debuts at Airshow

AP (July 30, 2014) — Smartphone powered paper airplane that was popular on crowdfunding website KickStarter makes its debut at Wisconsin airshow (July 30) Video provided by AP
Powered by NewsLook.com
U.K. To Allow Driverless Cars On Public Roads

U.K. To Allow Driverless Cars On Public Roads

Newsy (July 30, 2014) — Driverless cars could soon become a staple on U.K. city streets, as they're set to be introduced to a few cities in 2015. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



      Save/Print:
      Share:  

      Free Subscriptions


      Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

      Get Social & Mobile


      Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

      Have Feedback?


      Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
      Mobile iPhone Android Web
      Follow Facebook Twitter Google+
      Subscribe RSS Feeds Email Newsletters
      Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins