The research advances the engineering of artificial enzymes

While corrosion resistance, durability and low cost make plastic a very efficient resource, one of its main disadvantages is the damage it causes to the environment. According to a report by Greenpeace USA, 51 million tons of plastic waste were produced by households in the United States in 2021, with only 2.4 million tons being recycled, making it a pressing concern for the planet’s well-being.

To curb this problem, researchers are looking for ways to engineer enzymes capable of breaking down plastic – similar to how the body breaks down food during digestion.

Each of the roughly 30 trillion cells that make up the human body contains thousands of enzymes. Each enzyme helps the cell with important functions and processes such as digestion, cell regulation, and DNA replication, to name a few.

Scientists would like to harness this same power to tackle issues outside of biology, ranging from the aforementioned plastic breakdown to toxic waste treatment to chemical weapons remediation. The idea is to create enzymes that can perform reactions that nature has not yet evolved to do.

Engineered enzymes already work in some common household products. For example, the researchers found that by adding certain mutant enzymes to the detergent, it was possible to improve their ability to break down protein and fat residues on clothes in the form of food, grass or other stains. But like finding a needle in a haystack, one of the ongoing challenges for scientists is finding the right spot on a particular enzyme to improve its ability to promote a particular reaction.

University chemistry professors Ivan Korendovych and Olga Makhlynets and a team of researchers from Yokohama City University in Japan and the Vlaams Instituut voor Biotechnologie in Belgium have devised a simple method that uses directed evolution with nuclear magnetic resonance (NMR) to improve the enzyme engineering.

Similar to a magnetic resonance imaging (MRI) machine in the doctor’s office, which uses a magnetic field and radio waves to produce images of the body’s organs and tissues, NMR uses a magnetic field to highlight areas of an enzyme where beneficial mutations could be made . occurs. In a proof-of-concept study, the team turned myoglobin, an oxygen-storing protein, into the fastest artificial enzyme ever reported. Their results were recently published in the journal Nature.

When creating new enzymes for a particular chemical reaction, researchers look for an existing enzyme that works in a similar way. From there, scientists introduce mutations into this protein and look for improved activity.

While this sounds great in theory, Korendovych, lead author, says the process of enzyme engineering is like fishing in an ocean. “You’re not going to go to a place in the ocean where you know you probably won’t find fish,” he says. “With the method of directed evolution, we find areas that we know are good places to fish. If you have a better idea of ​​where to look, you have a better chance of finding those good mutations and creating new enzymes for practical and useful reactions ».

Directed evolution is a method used in protein engineering that mimics the process of natural selection to direct proteins toward a user-defined target. To refine an enzyme that catalyzes a specific chemical reaction, the research team used NMR to analyze potential samples in a test tube. The magnetic signals that change the most indicate the regions of the protein where beneficial mutations can occur.

Korendovych notes that the beauty of this method is that it provides a fairly simple way to narrow down the search space and identify points in the protein where researchers have the best chance of success.

“This will be a game changer in directed evolution,” says Korendovych. “Anybody can take their own enzyme, their own inhibitor for that enzyme, and do an NMR experiment and straight away without a lot of additional investment.”

The team says this method opens the door to endless enzyme possibilities. From creating green, engineered organisms to practical and useful chemistry without waste and organic solvents, this approach can help to be widely used in the field for various reactions.

“Ultimately, we think this will really unleash the power of directed evolution by making a la carte development of enzymes possible,” says Korendovych. “I believe this simple approach can help not only lead to the development of better catalysts but also generate new fundamental knowledge about enzymes.”