Nav: Home

New step towards clean energy production from enzymes

September 01, 2016

Oxygen inhibits hydrogenases, a group of enzymes that are able to produce and split hydrogen. This degradation is fatal for possible biotechnological applications of these enzymes for the production of clean energy. Understanding the mechanisms of this process is hence essential. An international team lead by researchers from UCL (UK) and CNRS (France), including an Ikerbasque Research Fellow from CIC nanoGUNE, have combined theory and experiment to characterize each chemical reaction step that results in the reduction of oxygen by the enzyme. These results have been published in the journal Nature Chemistry.

Fossil fuels supply over 80% of the world's energy. Since the energy crises in the 1970's and then in the 90's, when concerns appeared about greenhouse effects, the search for alternative energy sources has been ongoing. Hydrogen has been a particularly popular candidate because its combustion only produces water. Biotechnology is uniquely poised for providing a means for using hydrogen as a source of clean energy. One possibility is using enzymes called hydrogenases that naturally occur in various microorganisms that live in anaerobic ecosystems, such as some bacteria living in soil and in the intestinal tract of animals, or unicellular algae.

Hydrogenases catalyze the conversion of protons in hydrogen molecules (H2), whose combustion releases energy that can be utilized for example in fuel cells and therefore be part of biotechnological devices. The active site that catalyzes this reaction contains metallic ions (Iron or both Iron and Nickel). The Iron-only variety of hydrogenases is the most active for the production of hydrogen molecules. Their remarkably complex active site -the so-called H-cluster- is buried within the core of a large protein. A fatal problem for being able to exploit hydrogenases in biotechnological applications is that when brought to the aerobic conditions of a bioreactor (under normal oxygen pressures), molecular oxygen degrades their active site. Understanding the mechanism of the degradation process of the H-cluster is therefore essential to design a hydrogen-based fuel cell, but studies so far had not been conclusive.

To solve this conundrum, an international team of researchers has combined experiments, molecular simulations, and theoretical calculations. Using electrochemical methods, they have precisely measured the rates of the different reaction steps involved in the degradation of the enzyme by oxygen. They have studied the dependence of these rates on experimental parameters like the electrode potential, pH, H2O/D2O exchange, and mutation of specific amino acids in the protein. These results confirm predictions from theoretical calculations. On one hand molecular dynamics simulations, conducted by nanoGUNE's Ikerbasque Fellow David de Sancho, show the tunnels that oxygen follows to reach the active site of the protein, a necessary step for the degradation and to identify possible hot-spots for blocking these access tunnels. On the other, density functional theory has been used to elucidate the reaction products and evaluate the rate constants for the individual reaction steps.

The study published on August 22nd in Nature Chemistry has allowed to characterize unambiguously the complex reactions that occur in these large biological macromolecules using a highly innovative combination of computational and experimental approaches. "Although important challenges remain ahead for industrial applications, this study opens new avenues to efficiently exploit enzymes from living systems for clean energy production", says De Sancho.

Elhuyar Fundazioa

Related Hydrogen Articles:

Paving the way for hydrogen fuel cells
The hype around hydrogen fuel cells has died down, but scientists have continued to pursue new technologies that could enable such devices to gain a firmer foothold.
Keeping the hydrogen coming
A coating of molybdenum improves the efficiency of catalysts for producing hydrogen.
Hydrogen bonds directly detected for the first time
For the first time, scientists have succeeded in studying the strength of hydrogen bonds in a single molecule using an atomic force microscope.
Argon is not the 'dope' for metallic hydrogen
Hydrogen is both the simplest and the most-abundant element in the universe, so studying it can teach scientists about the essence of matter.
Metallic hydrogen, once theory, becomes reality
Nearly a century after it was theorized, Harvard scientists have succeeded in creating metallic hydrogen.
From theory to reality: The creation of metallic hydrogen
For more than 80 years, it has been predicted that hydrogen will adopt metallic properties under certain conditions, and now researchers have successfully demonstrated this phenomenon.
Artificial leaf goes more efficient for hydrogen generation
A new study, affiliated with Ulsan National Institute of Science and Technology has introduced a new artificial leaf that generates hydrogen, using the power of the Sun to mimic underwater photosynthesis.
Hydrogen from sunlight -- but as a dark reaction
The storage of photogenerated electric energy and its release on demand are still among the main obstacles in artificial photosynthesis.
New process produces hydrogen at much lower temperature
Waseda University researchers have developed a new method for producing hydrogen, which is fast, irreversible, and takes place at much lower temperature using less energy.
Hydrogen in your pocket? New plastic for carrying and storing hydrogen
A Waseda University research group has developed a polymer which can store hydrogen in a light, compact and flexible sheet, and is safe to touch even when filled with hydrogen gas.

Related Hydrogen Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Climate Crisis
There's no greater threat to humanity than climate change. What can we do to stop the worst consequences? This hour, TED speakers explore how we can save our planet and whether we can do it in time. Guests include climate activist Greta Thunberg, chemical engineer Jennifer Wilcox, research scientist Sean Davis, food innovator Bruce Friedrich, and psychologist Per Espen Stoknes.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...