Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Journal of Biological Chemistry: If oxygen becomes the undoing of proteins

12.10.2011
Journal of Biological Chemistry: Oxygen inactivates the enzyme function in three phases / RUB biologists publish a report on the first time-resolved model

Scientists from the Faculty of Biology and Biotechnology at the RUB have published a report in the Journal of Biological Chemistry explaining why enzymes used for the production of hydrogen are so sensitive to oxygen.


Synchrotron radiation source: The researchers from Bochum and Berlin investigated the hydrogenase protein using the Swiss Light Source at the Paul Scheerer Institute near Zurich. The figure also shows the 3-D structure of the protein. Photo: Camilla Lambertz


New model for enzyme inactivation: Oxygen inactivates the hydrogenase in three phases (left). The longer the enzyme is exposed to oxygen, the greater the number of oxygen particles that bind to the iron atoms of the hydrogenase (blue). This leads to a reduction in the number of bonds between the iron atoms and other atoms (green, black). They are thus no longer able to fulfill their function. The right-hand section of the illustration shows the hypothetical mechanism of the inactivation. Oxygen (O=O) binds to the di-iron center which leads to the development of an aggressive oxygen species. This attacks the four-iron center [4Fe4S], which suppresses its ability to generate hydrogen.

In collaboration with researchers from Berlin, they used spectroscopic methods to investigate the time course of the processes that lead to the inactivation of the enzyme’s iron center. “Such enzymes, the so-called hydrogenases, could be extremely significant for the production of hydrogen with the help of biological or chemical catalysts”, explains Camilla Lambertz from the RUB study group for photobiotechnology. “Their extreme sensitivity to oxygen is however a major problem. In future, our results could help to develop enzymes that are more robust.”

Oxygen as a friend and as an enemy

Oxygen is crucial for the survival of most animals and plants. It is however toxic for many living creatures if the concentration thereof is too high, and some organisms can even only exist entirely without oxygen. Sensitivity to oxygen is also present at the protein level. A large number of enzymes, for example, hydrogenases are known to be irreversibly destroyed by oxygen. Hydrogenases are biological catalysts that convert protons and electrons into technically usable hydrogen. The RUB team of Prof. Thomas Happe is doing research on so-called [FeFe]-hydrogenases which are capable of producing particularly large amounts of hydrogen. The generation of hydrogen takes place at the H-cluster, consisting of a di-iron and four-iron subcluster which, together with other ligands, form the reactive center.

Oxygen attacks the iron centers

The researchers, working in collaboration with Dr. Michael Haumann’s team in Berlin, discovered that oxygen binds to the di-iron center of the hydrogenase, which initiates the inactivation of another part of the enzyme consisting of four further iron atoms. In this project, sponsored by the BMBF, it was possible to show the diverse phases of the inactivation process for the first time using the so-called X-ray absorption spectroscopy. The researchers used the synchroton radiation source Swiss Light Source in Switzerland for this specific type of measurement. It generates particularly strong rays, thus enabling the characterization of metal centers in proteins. Amongst other things, the scientists thus determined the chemical nature of the iron centers and the distance from the surrounding atoms using atomic resolution.

Inactivation in three phases

The team of researchers from Bochum and Berlin used a new experimental procedure. They initially brought the hydrogenase sample into contact with oxygen for a few seconds to minutes and finally for a couple of hours and then suppressed all proceeding reactions by deep-freezing it in liquid nitrogen. The subsequently gained spectroscopic data was used for the development of a model for a three-phase inactivation process. According to this model, an oxygen molecule initially binds to the di-iron center of the hydrogenase, which leads to the development of an aggressive oxygen species. In the subsequent phase, this attacks and modifies the four-iron center. During the final phase, further oxygen molecules bind and the entire complex disintegrates. ”The entire process thus consists of a number of consecutive reactions that are distinctly separated in time”, says Lambertz. “The velocity of the entire process is possibly dependent on the phase during which the aggressive oxygen species moves from the di-iron to the four-iron center. We are currently elaborating further experiments to investigate this.”

Title

C. Lambertz, N. Leidel, K.G.V. Havelius, J. Noth, P. Chernev, M. Winkler, T. Happe, M. Haumann (2011) O2-reactions at the six-iron active site (H-cluster) in [FeFe]-hydrogenase, Journal of Biological Chemistry, doi: 10.1074/jbc.M111.283648

Further Information

Camilla Lambertz, Arbeitsgruppe Photobiotechnologie, Fakultät für Biologie und Biotechnologie der Ruhr-Universität Bochum, Tel. +49 234 32 24496

Camilla.Lambertz@rub.de

Thomas Happe, Arbeitsgruppe Photobiotechnologie, Fakultät für Biologie und Biotechnologie der Ruhr-Universität Bochum, Tel. +49 234 32 27026

Thomas.Happe@rub.de

Editor: Dr. Julia Weiler

Dr. Josef König | idw
Further information:
http://www.ruhr-uni-bochum.de/

More articles from Life Sciences:

nachricht Scientists first to develop rapid cell division in marine sponges
21.11.2019 | Florida Atlantic University

nachricht Machine learning microscope adapts lighting to improve diagnosis
21.11.2019 | Duke University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Machine learning microscope adapts lighting to improve diagnosis

Prototype microscope teaches itself the best illumination settings for diagnosing malaria

Engineers at Duke University have developed a microscope that adapts its lighting angles, colors and patterns while teaching itself the optimal...

Im Focus: Small particles, big effects: How graphene nanoparticles improve the resolution of microscopes

Conventional light microscopes cannot distinguish structures when they are separated by a distance smaller than, roughly, the wavelength of light. Superresolution microscopy, developed since the 1980s, lifts this limitation, using fluorescent moieties. Scientists at the Max Planck Institute for Polymer Research have now discovered that graphene nano-molecules can be used to improve this microscopy technique. These graphene nano-molecules offer a number of substantial advantages over the materials previously used, making superresolution microscopy even more versatile.

Microscopy is an important investigation method, in physics, biology, medicine, and many other sciences. However, it has one disadvantage: its resolution is...

Im Focus: Atoms don't like jumping rope

Nanooptical traps are a promising building block for quantum technologies. Austrian and German scientists have now removed an important obstacle to their practical use. They were able to show that a special form of mechanical vibration heats trapped particles in a very short time and knocks them out of the trap.

By controlling individual atoms, quantum properties can be investigated and made usable for technological applications. For about ten years, physicists have...

Im Focus: Images from NJIT's big bear solar observatory peel away layers of a stellar mystery

An international team of scientists, including three researchers from New Jersey Institute of Technology (NJIT), has shed new light on one of the central mysteries of solar physics: how energy from the Sun is transferred to the star's upper atmosphere, heating it to 1 million degrees Fahrenheit and higher in some regions, temperatures that are vastly hotter than the Sun's surface.

With new images from NJIT's Big Bear Solar Observatory (BBSO), the researchers have revealed in groundbreaking, granular detail what appears to be a likely...

Im Focus: New opportunities in additive manufacturing presented

Fraunhofer IFAM Dresden demonstrates manufacturing of copper components

The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM in Dresden has succeeded in using Selective Electron Beam Melting (SEBM) to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

First International Conference on Agrophotovoltaics in August 2020

15.11.2019 | Event News

Laser Symposium on Electromobility in Aachen: trends for the mobility revolution

15.11.2019 | Event News

High entropy alloys for hot turbines and tireless metal-forming presses

05.11.2019 | Event News

 
Latest News

Designer lens helps see the big picture

21.11.2019 | Interdisciplinary Research

Machine learning microscope adapts lighting to improve diagnosis

21.11.2019 | Life Sciences

Soft skin-like robots you can put in your pocket

21.11.2019 | Interdisciplinary Research

VideoLinks
Science & Research
Overview of more VideoLinks >>>