Featured Research

from universities, journals, and other organizations

Mimicking Nature, Scientists Can Now Extend Redox Potentials

Date:
November 5, 2009
Source:
University of Illinois at Urbana-Champaign
Summary:
New insight into how nature handles some fundamental processes is guiding researchers in the design of tailor-made proteins for applications such as artificial photosynthetic centers, long-range electron transfers, and fuel-cell catalysts for energy conversion.

Tuning redox potentials of a protein for energy conversions. A combination of water-repelling hydrophobicity (shown in red sphere) and hydrogen bonding interactions (shown in dotted orange lines) can fine-tune the redox potential of copper ion (shown in blue) in azurin in a wide range.
Credit: Graphic courtesy of Yi Lu

New insight into how nature handles some fundamental processes is guiding researchers in the design of tailor-made proteins for applications such as artificial photosynthetic centers, long-range electron transfers, and fuel-cell catalysts for energy conversion.

From rusting iron to forest fires to the beating of a human heart, oxidation-reduction reactions, which transfer electrons from one atom to another, are at the heart of many chemical and biological processes. Each process requires a particular redox potential, just as different electronic devices can require their own special battery.

How nature fine-tunes these potentials over a broad range with little change to the protein's electron-transfer properties or efficiency has largely remained a mystery.

Now, a team led by University of Illinois chemistry professor Yi Lu has unearthed nature's secret, and has utilized it to their advantage. The researchers describe their work in a paper to appear in the Nov. 5 issue of the journal Nature. "We show that two important interactions, hydrophobicity (water repelling) and hydrogen bonding, are capable of fine-tuning the reduction potential of a particular class of copper-containing proteins called cupredoxins," Lu said. "We extended the range both above and below what had previously been found in nature."

Lu, graduate student and lead author Nicholas M. Marshall, and their collaborators also show that the effects of hydrophobicity and hydrogen bonding are additive, which offers additional control and extends the range of redox (short for oxidation-reduction reaction) potentials beyond what nature, by itself, provides.

Previously, to cover a wide potential range, scientists had to use several different redox agents in conjunction. This made it difficult, if not impossible, to tune the redox potentials without changing other electron transfer properties or the efficiency.

Also, stable, water-soluble redox agents are rare, Lu said, and those that are available have a limited potential range. "Consequently, there is a huge demand for efficient, water-soluble redox agents with a wide potential range for environmentally friendly aqueous or biochemical studies," he said.

To unlock nature's secret, Lu's team studied the behavior of the cupredoxin, azurin. Cupredoxins are redox-active copper proteins that play crucial roles in many important processes, such as photosynthesis and cell signaling. Cupredoxins use a single redox-active center, whose reduction potential is tunable without compromising the structure and electron transfer properties of the protein.

The researchers found that two interactions -- hydrophobicity and hydrogen bonding -- can selectively raise or lower azurin's redox potential. The interactions occur not in the metalloprotein's innermost, primary core, but in a secondary sphere that surrounds the primary core.

Increasing the hydrophobicity in the secondary sphere can significantly increase the redox potential, the researchers report. The more this secondary region repels water, the more the overall charge on the copper ion becomes destabilized and the higher the potential becomes.

The effect of the hydrogen bonding interaction is subtler than the effect of hydrophobicity, Lu said. Hydrogen bonding can either increase or decrease electron densities around a residue that binds the copper ion in azurin, making the copper ion either easier or harder to reduce and thus slightly changing the redox potential.

"This was nature's secret," Lu said. "That by adjusting the hydrophobicity and the hydrogen bonding, we can raise or lower the redox potential, without changing the protein's electron-transfer properties or decreasing the protein's efficiency."

The result is a tailor-made redox agent that can be set with a very high potential, a very low potential, or with a potential somewhere in between.

"This unprecedented level of control over an electron-transfer protein was achieved by mapping out the major interactions," Lu said, "an approach that may apply to other redox proteins of interest, as well."

Lu is affiliated with the university's Beckman Institute, the departments of biochemistry, bioengineering, and materials science and engineering, the Frederick Seitz Materials Research Laboratory, and the Center of Biophysics and Computational Biology. The National Science Foundation and the National Institutes of Health funded the work.


Story Source:

The above story is based on materials provided by University of Illinois at Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University of Illinois at Urbana-Champaign. "Mimicking Nature, Scientists Can Now Extend Redox Potentials." ScienceDaily. ScienceDaily, 5 November 2009. <www.sciencedaily.com/releases/2009/11/091104132702.htm>.
University of Illinois at Urbana-Champaign. (2009, November 5). Mimicking Nature, Scientists Can Now Extend Redox Potentials. ScienceDaily. Retrieved April 20, 2014 from www.sciencedaily.com/releases/2009/11/091104132702.htm
University of Illinois at Urbana-Champaign. "Mimicking Nature, Scientists Can Now Extend Redox Potentials." ScienceDaily. www.sciencedaily.com/releases/2009/11/091104132702.htm (accessed April 20, 2014).

Share This



More Matter & Energy News

Sunday, April 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Small Reactors Could Be Future of Nuclear Energy

Small Reactors Could Be Future of Nuclear Energy

AP (Apr. 17, 2014) After the Fukushima nuclear disaster, the industry fell under intense scrutiny. Now, small underground nuclear power plants are being considered as the possible future of the nuclear energy. (April 17) Video provided by AP
Powered by NewsLook.com
Horseless Carriage Introduced at NY Auto Show

Horseless Carriage Introduced at NY Auto Show

AP (Apr. 17, 2014) An electric car that proponents hope will replace horse-drawn carriages in New York City has also been revealed at the auto show. (Apr. 17) Video provided by AP
Powered by NewsLook.com
Honda's New ASIMO Robot, More Human-Like Than Ever

Honda's New ASIMO Robot, More Human-Like Than Ever

AFP (Apr. 17, 2014) It walks and runs, even up and down stairs. It can open a bottle and serve a drink, and politely tries to shake hands with a stranger. Meet the latest ASIMO, Honda's humanoid robot. Duration: 00:54 Video provided by AFP
Powered by NewsLook.com
German Researchers Crack Samsung's Fingerprint Scanner

German Researchers Crack Samsung's Fingerprint Scanner

Newsy (Apr. 16, 2014) German researchers have used a fake fingerprint made from glue to bypass the fingerprint security system on Samsung's new Galaxy S5 smartphone. 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