A newly discovered family of enzymes might hold the key to converting plant waste into sustainable products like nylon, plastics, chemicals and fuels.
The new family of enzymes known as cytochrome P450 are active on the building blocks of lignin—the organic polymer that is deposited in the cell walls of plants, acts as scaffolding for plants, and is central to water delivery, while providing strength and defense against pathogens.
“This new cytochrome P450 enzyme can degrade a lot of different lignin-based substrates,” Gregg Beckham, PhD, from the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL), said in a statement. “That’s good because it means it can then be engineered to be a specialist for a specific molecule and we can evolve it further to push it in a certain direction.
“We now have one of the most well-known, versatile, engineerable and evolvable classes of enzymes ready to go as a foothold for biotechnology to move forward and make the enzyme better.”
Scientists have long attempted to efficiently break down lignin, one of the most complex components of plants.
“We have assembled an international team for the discovery and engineering of naturally occurring enzymes,” John McGeehan, a professor at the University of Portsmouth, said in a statement. “Enzymes are biological catalysts that can perform incredible reactions, breaking down some of our toughest natural and man-made polymers.
“To protect their sugar-containing cellulose, plants have evolved a fascinatingly complicated material called lignin that only a small selection of fungi and bacteria can tackle,” he added. “However, lignin represents a vast potential source of sustainable chemicals, so if we can find a way to extract and use those building blocks, we can create great things.”
According to McGeehan, cellulose and lignin are among the most abundant biopolymers on Earth. The international research team was able to release a crucial bottleneck in the process of breaking down lignin to basic chemicals providing a route to make new materials and chemicals.
The discovery also could lead to products created from lignin that will reduce the reliance on oil to make everyday products, offering an alternative to burning it to help reduce carbon dioxide emissions.
“There is a long-standing phrase—you can make anything out of lignin except money—but by harnessing the power of enzymes, this is set to change,” Sam Mallinson, a PhD student in structural biology at the University of Portsmouth and first author on the paper, said in a statement. “Using advanced techniques, from X-ray crystallography at the Diamond Light Source synchrotron, to advanced computer modelling, we have been able to understand the detailed workings of a brand new enzyme system.”
Earlier this year, a University of Georgia research team developed a new method to speed up the evolution of the P450 enzyme. The Portsmouth researchers are now collaborating with the team from Georgia to discover and evolve even faster enzymes for converting lignin into high-value sustainable products.
The study was published in Nature Communications.