Researchers at Freie Universitat Berlin and the Ruhr-Universitat Bochum have uncovered a crucial reaction principle of hydrogen-producing enzymes. Teams led by Dr Ulf-Peter Apfel in Bochum and Dr Sven Stripp at Freie Universitat investigated the production of molecular hydrogen in single-cell green algae.

They were able to demonstrate how the enzyme succeeds in transferring two electrons in succession to two hydrogen ions and thereby assume stable intermediate states.

Hydrogen gas is viewed as the energy source of the future. Thus, there is considerable industrial interest in elucidating the mechanism of biological production. The findings were published in the latest issue of the journal Angewandte Chemie.

In living nature a variety of chemical reactions take place very slowly. The use of enzymes increases the likelihood or the speed of a reaction (catalysis). Frequently the supply and removal of electrons also plays a role - this is referred to as reduction and oxidation.

Special enzymes, the hydrogenases, accelerate the conversion of hydrogen ions (protons) to hydrogen gas with high efficiency. They absorb excess electrons that are generated during photosynthesis and release hydrogen gas as a by-product.

This process can be described as a reduction of two protons with two electrons, whereby the reaction takes place in several steps.

"After receiving a first electron, an enzyme is typically less likely to accept a second one," stresses Sven Stripp.

In spite of this, two electrons can be transferred to two protons. Using synthetic hydrogenase enzymes, advanced infrared spectroscopy, and electrochemical methods, the researchers investigated how this is possible.

They demonstrated that the uptake of an electron at the catalytic center of the enzyme is coupled with the binding of a proton. The positive charge of the proton compensates for the negative charge of the electron.

In chemistry this process is known as proton-coupled electron transfer (PCET). "Thus, the second electron can be transferred with comparable probability as the first one," says Ulf-Peter Apfel.

According to the authors, this observation has high relevance for understanding the catalytic mechanism of hydrogenases and for the design of synthetic complexes for the production of hydrogen gas.

In addition, the scientists speculate that PCET processes could explain the uptake of multiple electrons in other enzymes as well because many of these macromolecules carry catalytic centers of iron and sulfur atoms, similar to those of hydrogenases.

Research paper

Tweet

Next generation solvent contributes to next generation biofuel production from biomass
Kanazawa, Japan (SPX) Dec 07, 2017
The first-generation biofuel, industrialized, ethanol, is produced from foodstuffs like maize, and thus poses great concern about a possible future shortage of food. It is therefore necessary to produce ethanol from non-food biomass like weeds, waste paper, paper cup, etc. (second-generation biofuel ethanol). Solvents needed for the production of second-generation biofuel ethanol known so far ar ... read more

Related Links
Ruhr-University Bochum
Bio Fuel Technology and Application News

Thanks for being here; We need your help. The Space Media Network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceMediaNetwork Contributor $5 Billed Once credit card or paypal		SpaceMediaNetwork Monthly Supporter $5 Billed Monthly paypal only