Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Researchers Discover Molecular Gatekeeper in Enzyme

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:

More articles from Life Sciences:

nachricht Biologists unravel another mystery of what makes DNA go 'loopy'
16.03.2018 | Emory Health Sciences

nachricht Scientists map the portal to the cell's nucleus
16.03.2018 | Rockefeller University

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

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...

Im Focus: Surveying the Arctic: Tracking down carbon particles

Researchers embark on aerial campaign over Northeast Greenland

On 15 March, the AWI research aeroplane Polar 5 will depart for Greenland. Concentrating on the furthest northeast region of the island, an international team...

Im Focus: Unique Insights into the Antarctic Ice Shelf System

Data collected on ocean-ice interactions in the little-researched regions of the far south

The world’s second-largest ice shelf was the destination for a Polarstern expedition that ended in Punta Arenas, Chile on 14th March 2018. Oceanographers from...

Im Focus: ILA 2018: Laser alternative to hexavalent chromium coating

At the 2018 ILA Berlin Air Show from April 25–29, the Fraunhofer Institute for Laser Technology ILT is showcasing extreme high-speed Laser Material Deposition (EHLA): A video documents how for metal components that are highly loaded, EHLA has already proved itself as an alternative to hard chrome plating, which is now allowed only under special conditions.

When the EU restricted the use of hexavalent chromium compounds to special applications requiring authorization, the move prompted a rethink in the surface...

Im Focus: Radar for navigation support from autonomous flying drones

At the ILA Berlin, hall 4, booth 202, Fraunhofer FHR will present two radar sensors for navigation support of drones. The sensors are valuable components in the implementation of autonomous flying drones: they function as obstacle detectors to prevent collisions. Radar sensors also operate reliably in restricted visibility, e.g. in foggy or dusty conditions. Due to their ability to measure distances with high precision, the radar sensors can also be used as altimeters when other sources of information such as barometers or GPS are not available or cannot operate optimally.

Drones play an increasingly important role in the area of logistics and services. Well-known logistic companies place great hope in these compact, aerial...

All Focus news of the innovation-report >>>



Industry & Economy
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

International Virtual Reality Conference “IEEE VR 2018” comes to Reutlingen, Germany

08.03.2018 | Event News

Latest News

Wandering greenhouse gas

16.03.2018 | Earth Sciences

'Frequency combs' ID chemicals within the mid-infrared spectral region

16.03.2018 | Physics and Astronomy

Biologists unravel another mystery of what makes DNA go 'loopy'

16.03.2018 | Life Sciences

Science & Research
Overview of more VideoLinks >>>