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 Mlheim 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 Mlheim. 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. T
Contact: Dr. Johannes Messinger