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 New risk factors for anxiety disorders
24.02.2017 | Julius-Maximilians-Universität Würzburg

nachricht Stingless bees have their nests protected by soldiers
24.02.2017 | Johannes Gutenberg-Universität Mainz

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Stingless bees have their nests protected by soldiers

24.02.2017 | Life Sciences

New risk factors for anxiety disorders

24.02.2017 | Life Sciences

MWC 2017: 5G Capital Berlin

24.02.2017 | Trade Fair News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>