With the aid of quantum chemistry they were able to provide unexpected insight into the properties of the oxygen evolving complex (OEC). The OEC is the catalyst in plants that splits water using sunlight in order to build carbohydrates, thus powering all life on earth.
Figure (copyright by MPI CEC): The two structures of the core of nature's water oxidizing catalyst Photosystem II, which interconvert by changing bonds between an oxygen and its two manganese bondingpartners; a different spectroscopic signal is produced by eacharrangement.
Its precise structure, which was showing enigmatic spectroscopic behaviour, could now finally be solved with the aid of quantum chemistry. In one of its most studied oxidation states the OEC revealed two types of spectroscopic signals.
These signals could be converted to one another by various treatments, but not in any structurally comprehensible way. Moreover the signals are so complex that a detailed molecular structure could not be deduced. With the aid of theoretical spectroscopic techniques, Dr. Dimitrios Pantazis, scientist at the MPI CEC, and his colleagues were able to show that the two signals are caused by two energetically similar and interconvertible structures of the complex.
The core of the enzyme consists of a partial cubic structure made of manganese, calcium and oxygen (Mn4CaO5 s. figure). "Calculations show, that the two structures differ only by one bond, that swaps between the central oxygen and the two terminal manganese atoms", states Pantazis. This small change has a huge impact on the electronic structure and thus the spectroscopic properties of the molecule. Both structures are almost equal in energy and the bond swapping can happen over a low energetic barrier. Crucially, the scientists at the MPI additionally proved using theoretical simulations that each of the two structures has a distinct spectroscopic signature and that these two signatures have a one-‐to-‐one correspondence with the experimentally observed spectroscopic signals.
The deep understanding of the OEC is fundamental in order to further elucidate nature´s mysteries on the oxidation of water, a reaction that plays an essential role for energy research, such as in artificial photosynthesis. After these striking findings, research by Pantazis and his group is currently focused on identifying whether the oxygen atom swapping bonds with the manganese is one of the oxygen atoms released from the enzyme as molecular oxygen.
The new findings will shed light on the kinetics and exchange of water molecules that take part in the reaction, paving the way for a detailed atomic-‐level understanding of the mechanism of water oxidation.
Published online in Angewandte Chemie International Edition, August 21 http://dx.doi.org/10.1002/anie.201204705
The Max Planck Institute for Chemical Energy Conversion (MPI CEC) in Muelheim an der Ruhr focuses on fundamental chemical reactions that play a role for the storage and conversion of energy. The main objective is to save the energy of sunlight in small, energy rich molecules, and thus make it easily available independently of time and location. In the three departments Heterogeneous Reactions, Molecular Theory and Spectroscopy and Biophysical Chemistry work 75 scientists from more than 20 countries and with their expertise they contribute to a sustainable energy concept.
Dr. Rebekka Loschen | Max-Planck-Institute
Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University
How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy