Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers Discover Molecular Gatekeeper in Enzyme

18.02.2009
Researchers from Wageningen University, along with colleagues from the University of Groningen and the University of Pavia (Italy), have unravelled the mechanism that plays a role in the natural production of vitamin C. In this process, a molecular gatekeeper blocks the entrance to the reaction centre of a crucial enzyme.

The article in which the team reports its finding has been declared Paper of the Week by the Journal of Biological Chemistry, an honour given to only one in every hundred articles.

The biological production of vitamin C in plants, fungi and many animals is a complicated process that involves enzymes. A large group of these catalysts need oxygen to function well. In plants, a chemical, cytochrome C, replaces the function of oxygen. Cytochrome C or oxygen ensures that the co-factor flavin in the enzyme's action centre is brought back to its original state after reaction. Because of this restoration, the enzyme is ready for a new reaction.

The research team wondered why the one group of enzymes reacted with oxygen and the other, closely related group did not. How does the oxygen reach the centre of the enzyme, which consists of about 500 hundred linked building blocks (amino acids) of different sizes and forms. This string of building blocks is, as it were, bunched up into a little lump with 'holes, caverns and tunnels' in between. Oxygen has to seep through this little lump or clear a path through the tangle of amino acids in order to penetrate the hidden flavin in the centre.

Imagine, the researchers said, that in some enzymes oxygen can reach the enzyme's centre through tunnels and holes. You should then be able to discover the route using the structure. Unfortunately, there was no crystalline structure of the enzyme in question on hand. There was, however, one other possibility. By laying side by side all of the individual building blocks of the enzymes that react with oxygen and those that do not, the differences should become clear.

Comparing both analyses brought a subtle difference to light. Only one building block, number 113, at the end of a possible route turned out to be a bit different. This difference relates to the amino acid alanine. When alanine was replaced by the smaller building block glycine at that position, it turned out that the enzyme was suddenly oxygen permeable. And not just a little bit. The difference is so large it's as if a dam has burst: a factor of 400.

How is it possible that one building block in a construction of 500 blocks can have so much effect? The researchers support the tunnel theory: the building block alanine has four different protrusions, while glycine has only three. Alanine's extra protrusion, a methyl group, blocks the tunnel and prevents oxygen from penetrating the centre. At this site, alanine works as a gatekeeper and it keeps the door tightly shut.

But, why isn't the gate just simply open? Evidently, having a strict gatekeeper has its advantages. It turns out that the aggressive substance hydrogen peroxide ('domestic bleach') forms in the reaction with oxygen. Hydrogen peroxide accelerates the ageing of cells and a plant, which makes a lot of vitamin C, does not like this.

The way is now open to prepare vitamin C in a natural way. However, the chemical route already exists, is cheap and yields an identical product. The deciphered mechanism is, however, also applicable to similar biochemical reactions, for example, the preparation of vanilla. Additionally, the deciphered process can mean a step forward in synthetic biology in which products that do not occur or hardly occur in nature can be produced in a natural way.

Jac Niessen | alfa
Further information:
http://www.wur.nl
http://www.wur.nl/UK/newsagenda/news/Gatekeeper090216.htm

More articles from Life Sciences:

nachricht Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory

nachricht Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>