Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Get to Work, Enzymes!

High yield: Cell-free enzyme cascade makes hydrogen from xylose

Fuel cells are a highly promising means of producing electricity. However, the hydrogen they require is still largely obtained from coal, oil, or natural gas. Producing hydrogen from less expensive biomass is an attractive alternative, but has not produced sufficient yields to date.

In the journal Angewandte Chemie, a team of American and Mexican researchers has now introduced a cell-free biosystem of thirteen enzymes that can produce hydrogen from xylose, one of the main components of plants, in yields of over 95 %.

Xylose is a pentose (a sugar molecule containing five carbon atoms), and is one of the main building blocks of lignocellulosic biomass—wood and parts of woody plants. It is not economically feasible to separate xylose from the other components of biomass for the production of hydrogen. There are microorganisms that can convert xylose and glucose, the building block that makes up cellulose, into hydrogen. However, the yields are very low.

Y.-H. Percival Zhang at Virginia Tech (Blacksburg, USA) and his co-workers in the USA and Mexico have thus resorted to a trick: They are using the enzymes used by the microorganisms, but in a cell-free system. They combined thirteen enzymes and various cofactors like NADPH into a complex cascade that do not exist in the natural metabolic systems. In a bioreactor, they were able to produce hydrogen from xylose with a yield of over 95 %.

The downside: In the first step of the reaction, xylose is isomerized into xylulose, which must be activated in a second step by addition of a phosphate group. This requires ATP (adenosine triphosphate), the "energy carrier" of cells, to "pump" chemical energy into the enzyme cascade. Unfortunately, ATP is a very expensive material. The thing that depends on ATP is the splitting of the energy-rich bonds between individual phosphate groups. The researchers thus had an idea: They wanted to replace the ATP with a more economical substance, polyphosphate, which also contains energetic phosphate bonds. However, this requires a xylulokinase, an enzyme that attaches phosphate groups to xylulose, and can use polyphosphate instead of ATP.

Polyphosphate is found in volcanic rocks and in deep-oceanic steam vents. Primeval organisms may have used this substance. The researchers isolated the gene for a xylulokinase from thermotoga maritima, a thermophilic microorganism found in such environments, and used genetic engineering to produce the enzyme. As they hoped, this enzyme can also use polyphosphate and can successfully replace the ATP-dependent xylulokinase in the enzyme cascade.

This team had previously developed a synthetic enzymatic route for the production of hydrogen from cellulose. Now both of the major components of biomass, cellulose and xylose, can be converted together in a new approach for the more economical production of hydrogen.

About the Author
Dr Percival Zhang is an Associate Professor of Biological Systems Engineering Department in the College of Agriculture and Life Sciences and the College of Engineering at Virginia Tech and has been working in the biofuels area for over 15 years. One of his goals are to replace crude oil with renewable sugars. He is the recipient of the Biotechnology and Bioengineering Daniel IC Wang Award and DuPont Young Faculty Award.

Author: Y.-H. Percival Zhang, Virginia Tech, Blacksburg (USA),

Title: High-Yield Production of Dihydrogen from Xylose by Using a Synthetic Enzyme Cascade in a Cell-Free System

Angewandte Chemie International Edition, Permalink to the article:

Y.-H. Percival Zhang | Angewandte Chemie
Further information:

More articles from Life Sciences:

nachricht Make way for the mini flying machines
21.03.2018 | American Chemical Society

nachricht New 4-D printer could reshape the world we live in
21.03.2018 | American Chemical Society

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

Im Focus: Tiny implants for cells are functional in vivo

For the first time, an interdisciplinary team from the University of Basel has succeeded in integrating artificial organelles into the cells of live zebrafish embryos. This innovative approach using artificial organelles as cellular implants offers new potential in treating a range of diseases, as the authors report in an article published in Nature Communications.

In the cells of higher organisms, organelles such as the nucleus or mitochondria perform a range of complex functions necessary for life. In the networks of...

Im Focus: Locomotion control with photopigments

Researchers from Göttingen University discover additional function of opsins

Animal photoreceptors capture light with photopigments. Researchers from the University of Göttingen have now discovered that these photopigments fulfill an...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

International Tinnitus Conference of the Tinnitus Research Initiative in Regensburg

13.03.2018 | Event News

Latest News

TRAPPIST-1 planets provide clues to the nature of habitable worlds

21.03.2018 | Physics and Astronomy

The search for dark matter widens

21.03.2018 | Materials Sciences

Natural enemies reduce pesticide use

21.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>