Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Electrons travel through proteins like urban commuters

02.02.2007
For Duke University theoretical chemist David Beratan, the results of his 15 years of studying how electrons make their way through some important protein molecules can be summed up with an analogy: how do big city dwellers get from here to there?

It's often swiftest to take the subway, Beratan notes, but riders may sometimes elect to alter their route by exiting the train for a short cab ride or a walk down the street. And they also may have to work around a route that is temporarily out of service.

In the Friday, Feb. 2, issue of the journal Science, Beratan and two co-authors use similar logic to describe their unified description of electron movements through certain "electron-transfer" proteins that lie at the heart of many processes essential for life. Such processes include harvesting light in photosynthesis in plant cells and generating energy in animal cells.

The research was funded by the National Institutes of Health.

... more about:
»Beratan »Protein »electron-transfer

"I think we have discovered the physical framework for thinking about all such protein electron-transfer chemistry," Beratan said. "Having this rule book in place will let scientists pose some hard but interesting questions about evolutionary pressures on protein structures.

"Another payoff may be new insight for designing biologically based artificial systems that, for instance, can capture solar energy or make fertilizer from air," he added.

For more than 50 years, theoreticians have been pondering the most likely itineraries that electrons follow through electron-transfer proteins, Beratan said. These proteins "are believed to shuttle electrons around, one at a time, but not to do any chemistry that involves the forming or breaking of chemical bonds," he said.

Earlier theoretical work from Beratan's group indicated that electrons can take short cuts through the proteins by following the spooky guidelines of quantum mechanics.

That means the electrons may sometimes leak from one chemical bond to a neighboring bond, he said. They also can take forbidden walks on the wild side by tunneling through open space.

Those findings prompted scientists to conjecture that electron-transfer proteins actually evolved their shapes to allow electrons the option of using quantum rules in negotiating molecular folds and crevices. The possibilities of such quirky routing options have vastly increased the challenge for theoreticians such as Beratan.

Using ever larger networks of computers to calculate the most favorable routes of electron travel, Beratan and his colleagues analyze these proteins in much the same way that commuters pore over transportation maps to plot the fastest destination routes.

The key insight to their current study arose from understanding that as the proteins' atoms jiggle around, the "subway maps" change dynamically.

Beratan said their extended computer analyses have been aided by an experimental team from the California Institute of Technology that has been documenting where electrons are moving by attaching extra chemical groups at various positions on protein surfaces. Shining laser light on these chemical groups enables researchers to monitor the movement of electrons.

The Caltech experiments, prompted in part by the predictions of Beratan's group, showed several years ago that the swiftest electron routes can sometimes be longer than expected, because electrons move fastest along chemically bonded pathways.

In contrast, electrons move much slower if they must tunnel through empty space. But the through-space routes can actually prove optimal if they enable electrons to make major shortcuts.

"You can think about a through-bond network being analogous to taking a subway route, and a through-space connection being analogous to walking or taking a bus between subway stops," Beratan said.

New analyses reported by Beratan's group have uncovered that more complicated routings are important in some electron-transfer proteins. There can be multiple pathways that fluctuate in importance as the protein atoms move around. "We can capture those pathway fluctuations only by doing combined quantum mechanical and classical, standard calculations, which we're now able to do," he said.

The new report describes the mixed quantum-classical analysis of likely electron pathways in the electron-transfer protein cytochrome b562.

The analysis uncovered that at seven locations on the protein, electrons took multiple fluctuating pathways. "So there is always a rapid commuter route available, even if the favorite train is out of order," he said.

In two other locations, the protein offers only one dominant but slow route. There the electron has no choice but to tunnel through an especially slow bottleneck presented by the protein's structure.

"After we saw this compelling bimodal behavior in cytochrome b562, we wondered whether this behavior was general among electron-transfer proteins," Beratan said. "And we've found that all of the proteins we have looked at have this same behavior.

"I think we're able to explain why there is this dichotomy, and why some electron-transfer rates have a quite remarkable dependence on protein structure while others don't," he said. "I believe we now have a unified view of many years' worth of experimental data."

Monte Basgall | EurekAlert!
Further information:
http://www.duke.edu

Further reports about: Beratan Protein electron-transfer

More articles from Life Sciences:

nachricht Transport of molecular motors into cilia
28.03.2017 | Aarhus University

nachricht Asian dust providing key nutrients for California's giant sequoias
28.03.2017 | University of California - Riverside

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers shoot for success with simulations of laser pulse-material interactions

29.03.2017 | Materials Sciences

Igniting a solar flare in the corona with lower-atmosphere kindling

29.03.2017 | Physics and Astronomy

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

29.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>