Research advances understanding of how hydrogen fuel is made

October 5, 2005
Research advances understanding of how hydrogen fuel is made

Oxygen may be necessary for life, but it sure gets in the way of making hydrogen fuel cheaply and abundantly from a family of enzymes present in many microorganisms. Blocking oxygen’s path to an enzyme’s production machinery could lead to a renewable energy source that would generate only water as its waste product.

Image: Schematic diagram of hydrogen-oxygen reaction taking place in hydrogenase CpI. (Graphic courtesy of Jordi Cohen)

Researchers at the Beckman Institute for Advanced Science and Technology at the University of Illinois at Urbana-Champaign have opened a window by way of computer simulation that lets them see how and where hydrogen and oxygen travel to reach and exit an enzyme’s catalyst site – the H cluster – where the hydrogen is converted into energy.

The Illinois scientists and three colleagues from the National Renewable Energy Laboratory in Golden, Colo., detailed their findings in the September issue of the journal Structure. What they found could help solve a long-standing economics problem. Because oxygen permanently binds to hydrogen in the H cluster, the production of hydrogen gas is halted. As a result, the supply is short-lived.

Numerous microorganisms have enzymes known as hydrogenases that simply use sunlight and water to generate hydrogen-based energy.

“Understanding how oxygen reaches the active site will provide insight into how hydrogenase’s oxygen tolerance can be increased through protein engineering, and, in turn, make hydrogenase an economical source of hydrogen fuel,” said Klaus Schulten, Swanlund Professor of Physics at Illinois and leader of the Beckman’s Theoretical Biophysics Group.

Using computer modeling developed in Schulten’s lab – Nanoscale Molecular Dynamics (NAMD) and Visual Molecular Dynamics (VMD) – physics doctoral student Jordi Cohen created an all-atom simulation model based on the crystal structure of hydrogenase CpI from Clostridium pasteurianum.

This model allowed Cohen to visualize and track how oxygen and hydrogen travel to the hydrogenase’s catalytic site, where the gases bind, and what routes the molecules take as they exit. Using a new computing concept, he was able to describe gas diffusion through the protein and predict accurately the diffusion paths typically taken.

“What we discovered was surprising,” Schulten said. “Both hydrogen and oxygen diffuse through the protein rather quickly, yet, there are clear differences.”

Oxygen requires a bit more space compared with the lighter and smaller hydrogen, staying close to few well localized fluctuating channels. The hydrogen gas traveled more freely. Because the protein is more porous to hydrogen than to oxygen, the hydrogen diffused through the oxygen pathways but also through entirely new pathways closed to oxygen, the researchers discovered.

The researchers concluded that it could be possible to close the oxygen pathways of hydrogenase through genetic modification of the protein and, thereby, increase the tolerance of hydrogenases to oxygen without disrupting the release of hydrogen gas.

Co-authors with Schulten and Cohen were Kwiseon Kim, Paul King and Michael Seibert, all of the National Renewable Energy Laboratory. The National Institutes of Health, National Science Foundation and the U.S. Department of Energy funded the research.

NAMD is a parallel molecular dynamics code designed for high-performance simulation of large biomolecular systems. VMD is a molecular visualization program for displaying, animating and analyzing large biomolecular systems using 3-D graphics.

Source: University of Illinois at Urbana-Champaign

Explore further: What is interplanetary dust and can it spread the ingredients of life?

Related Stories

Microbes map path toward renewable energy future

November 11, 2015

In the quest for renewable fuels, scientists are taking lessons from a humble bacterium that fills our oceans and covers moist surfaces the world over. While the organism captures light to make food in a process called photosynthesis, ...

New class of DNA repair enzyme discovered

October 29, 2015

This year's Nobel Prize in chemistry was given to three scientists who each focused on one piece of the DNA repair puzzle. Now a new study, reported online Oct. 28 in the journal Nature, reports the discovery of a new class ...

Saturn's moon Titan

October 5, 2015

In ancient Greek lore, the Titans were giant deities of incredible strength who ruled during the legendary Golden Age and gave birth to the Olympian gods we all know and love. Saturn's largest moon, known as Titan, is therefore ...

Photosynthesis gene can help crops grow in adverse conditions

September 18, 2015

A gene that helps plants to remain healthy during times of stress has been identified by researchers at Oxford University. Its presence helps plants to tolerate environmental pressures like drought—and it could help create ...

Recommended for you


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.