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: The body relies on thousands of sugar–protein complexes to stay healthy

Related Stories

Protecting resources from oxygen damage

June 20, 2017

Vital to life on this planet, oxygen has a sinister and ravenous side that harms plants and biofuel production. That's why the Department of Energy's Office of Science supports research to tame oxygen's dark side.

Hydrogen bonds directly detected for the first time

May 12, 2017

For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope. Researchers from the University of Basel's Swiss Nanoscience Institute network ...

What can we learn from dinosaur proteins?

April 24, 2017

DNA might get all the attention, but proteins do the work. The recent confirmation that it is possible to extract proteins—which are encoded by DNA and perform all of the functions that keep living cells alive—from 80-million-year-old ...

Recommended for you

How artificial intelligence is taking on ransomware

June 28, 2017

Twice in the space of six weeks, the world has suffered major attacks of ransomware—malicious software that locks up photos and other files stored on your computer, then demands money to release them.

0 comments

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.