Designer enzymes from exotic building blocks
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- The Biocatalysis 2021 project ¬P29 is focused on enzyme engineering based on expansion of the genetic code. Source: N. Budisa
02.01.2014 -
Nature uses 20 different amino acids as building blocks for proteins. With the assistance of a few molecular biological slights-of-hand, however, it is possible to create significantly higher number of different types of amino acids. In turn, these can result in proteins with completely new properties. The researchers in the Cluster Biocatalysis2021 are now exploring whether these kinds of designer enzymes are also suitable for the field of industrial production. The cooperative project P29, which is funded by the German Federal Ministry of Education and Research (BMBF), is currently breaking new ground in the field of enzyme engineering. With the help of exotic amino acids, the involved scientists are busy working on the creation of enzymes that will one day be put to work in the production of cosmetics and detergents.
At the intellectual level the project began as long as four years ago when three researchers had a bold vision that has now come to life as a Biocatalysis 2021 project. The BMBF is funding the project with around 560,000 euros over three years until 2013. The objective is to create enzymes with novel characteristics that can carry out biochemical reactions on an industrial scale. “The production of cold-wash lipases, i.e. enzymes that work at low temperatures and which can easily remove dirt from the laundry, is the dream of all of the researchers here,” says Nediljko Budisa, coordinator of the Biocatalysis2021 project and a professor at the Technical University of Berlin’s Institute of Chemistry.
| Biocatalysis2021 |
| More information about the project: click here |
Trio of enzyme experts
Another of the trio of researchers is microbiologist Garabed Antranikian, President of the Technical University of Hamburg: His team and a Japanese partner are isolating extremophile microorganisms from the deep ocean floor. These contain enzymes such as lipases and esterases that have unusual properties. The Hamburg scientists the isolate these super-enzymes, subject them to microbiological characterisation, and make them available for the project. Structural biologist Matthias Wilmanns from the European Molecular Biology Laboratory in Heidelberg is responsible for structure ¬elucidation: Through the use of crystallographic methods, he is able to make visible the three-dimensional form of the enzymes. In turn, this tells the researchers the points on which the substrate, i.e. the substance to be converted, should bind to the enzyme.
The third member of the P29 team is molecular biologist and chemist Nediljko Budisa, who applies his expertise in the field of enzyme optimisation, and decides the changes that need to be made to the molecules. “For example, here a bit more hydrophobicity, there a little bit of polarity, and so on,” explains the Croatian-born coordinator. At this point, however, the scientists have come up against the limits of classical chemistry. “Attaching chemical groups on the enzymes can’t be done in a targeted manner, but is more trial and error,” says the Berlin-based professor.
The P29-consortium has thus opted for a different approach to enzyme optimisation, which they call ‘Expanding the Genetic Code’. The trio of scientists have turned their attentions to extending the genetic code, and are incorporating amino acids into the engineered enzymes that do not occur in nature and which also have novel properties. The experts refer to these as ‘non-canonical’ amino acids.
Improving the lipase of an extremophile bacterium
The feasibility of this method has been demonstrated using the example of one of the lipases isolated by Antranikian. “Normally you have to heat the lipase from Thermoanaerobacter thermohydrosulfuricus up to 90 degrees in order for it to be activated. That doesn’t make sense from an energy perspective,” says Budisa. “By making changes in the genetic code, we could incorporate a non-canonical amino acid in the protein, and thus enable the enzyme to be active even at room temperature.”
This first pilot project has to date worked only on the small laboratory scale. To arouse the interest of industry, however, researchers must now re-scale their work and test the reaction on a larger scale. “After a year of project work I can say in retrospect that we are well proven as a team and that we can already claim partial success,” emphasises Budisa. In the next step, the researchers want to optimise other enzymes to determine the universality of the new technology. “At the end of the day, we want to prove that our first project was more than just a lucky score.”
Author: Andrea van Bergen
