Scientists worldwide have previously succeeded in identifying enzymes that are able to break down similar materials, but these enzymes were characterized by low efficiency. Large amounts of the enzyme were therefore required in order to break down the nerve agent, rendering their use impractical.
This is where Prof. Dan Tawfik of the Weizmann Institute's Biological Chemistry Department enters the picture. Tawfik's group developed a special method to artificially induce "natural selection" of enzymes in a test tube, enabling them to engineer "tailor-made" enzymes.
The method is based on introducing many mutations to an enzyme, and scanning the variety of mutated versions that were created in order to identify those that exhibit improved efficiency. These improved enzymes then repeatedly undergo further rounds of mutations and selection for higher efficiency. In previous studies, Tawfik showed that this method can improve the efficiency of enzymes by factors of hundreds and even thousands.
For the current task, Tawfik selected an enzyme that has been extensively studied in his laboratory, known as PON1. The main role of this enzyme, found naturally in the human body, is to break down the products of oxidized fats that accumulate on blood vessel walls, thus preventing atherosclerosis. But PON1 seems to be a bit of a "moonlighter" as it has also been found to degrade compounds belonging to the family of nerve agents.
However, because this activity has not fully evolved and developed through natural selection, its efficiency in carrying out the task remains very low. But by using the directed evolution method, scientists hope that they will be able to evolve this random "moonlighting" activity into PON1's main "da
|Contact: Yivsam Azgad|
Weizmann Institute of Science