Czech scientists developed a new method for improving the functional characteristics of enzymes

An international team of scientists from the Czech Republic, Germany and Japan have developed a new method for improving the properties of enzymes. The method has potential for wide application in the chemical, medicinal and food industries. The procedure has been published in the August issue of prestigious scientific magazine Nature Chemical Biology.

Degradation of toxic substances

The modified enzymes can be used, for example, for disposal of highly harmful chemical substances which enter into the environment as a result of human activity and can have a very negative influence on human and animal health. Nature cannot degrade many of these chemicals but, in this work, the scientists have developed an approach that can be applied to remove them efficiently from the environment.

Finding an agent that would successfully clean up chemical toxins has been a kind of theoretical Holy Grail for chemists. Thanks to a group of scientists at Brno's Masaryk University it seems the quest is over.

The main discovery describes a method, a new approach that can be used to tailor enzymes. So the method should be universal and can be applied to many other enzymes, some of them could be of great practical use, so it could be put to use very quickly.

New method of genetic manipulation

The principle of the discovery is based on genetic manipulation of the enzyme which is starting and accelerating the chemical reaction. So far the scientists had focused during the modification of the enzyme qualities on the site in its structure where the chemical reaction happens, the active site. The new method is based on the modification of so-called access tunnels that connect the active site with the surface of the enzyme.

„Now we can use genetic modifications for changing the properties of the enzymes so they can faster and more easily dispose of harmful substances in the environment," says Dr. Jiří Damborský, leader of the Protein Engineering Group at the Institute of Experimental Biology, Faculty of Science, Masaryk University. "We have developed an engineered enzyme in our laboratory called haloalkane dehalogenase, the enzyme can be used to decontaminate various compounds. And this particular enzyme was developed to have improved activity with the highly toxic substance 1,2,3-trichloropropane (TCP)."

This colourless liquid TCP is a secondary product of chemical production. It can resist in the soil or underground waters more than 100 years, it is highly toxic for water organisms and contributes to genesis of human cancer. Using the new approach, the protein engineers developed a modified enzyme capable of degrading this substance 32 times faster than the original enzyme. The enzyme can be used for decontaminating various substances. Its specificity is very broad, it can convert over a hundred different compounds.

Widely usable method

The method has much wider scope of use then just in the fight with harmful substances and in the environmental protection. The targeted modification of enzymatic structure in the sites important for its function can change the qualities of enzymes utilized in different areas. For example, the method can be used to produce some high-value chemicals, when can then be used to synthesize drugs.

„We know there are some companies that have tried to develop such technology in the past but they couldn't put it into practice. So maybe now they can use our enzyme and the technology will work," says Damborský. Scientific teams from Institute Pasteur in France, University of Vienna in Austria or Weizmann Institute in Israel have already evinced the interests in the method.

Picture: Hot spot residues lining the access tunnels selected for mutagenesis by computer simulations. Left: Cartoon model of wild-type DhaA. Gray, main domain; white, cap domain; yellow, product release pathway corresponding to the main tunnel; blue, product release pathway corresponding to the slot tunnel; green, residues selected for mutagenesis. Right: Ball and stick model of the residues selected for mutagenesis.

Author: Dagmar Smětalová
Sources:
http://www.sciencedaily.com/releases/2009/09/090924101117.htm
http://www.muni.cz/events/calendar/3888?lang=en
http://www.radio.cz/en/article/120192