Scientists in the US have created an artificial enzyme that can digest the most complex and most resistant part of wood polymer – lignin, which can be used as a renewable energy source.
Lignin is found in all vascular plants: it forms cell walls, gives rigidity, allows trees to stand, and occupies 20-35% of the weight of wood. The polymer gives foods a smoky flavor when roasted over a fire and is the second renewable carbon source on Earth.
In nature, lignin is broken down by fungi and bacteria, but these enzymes are expensive, degrade quickly, and are difficult to use in production. Scientists for a long time could not create a biomass processing method that would “digest” this wood polymer.
Researchers have simplified the decomposition process of plant biomass with the help of a synthetic enzyme. In terms of properties and structure, its molecules are similar to proteins from the class of peroxidases, with the help of which bacteria and fungi decompose lignin filaments in rotting deadwood.
The team replaced some of the amino acid chains in the enzyme with peptoids. Unlike proteins, these organic molecules are resistant to heat and other destabilizing effects. Thanks to peptoids, peroxidases became more stable and chemically active: the molecules successfully decomposed lignin and withstood heating up to 60 degrees Celsius, which wasn’t possible with all other natural proteins.
“We have succeeded in creating the first nature-like enzyme that can quickly degrade lignin and turn it into a set of molecules that can be used as biofuels or raw materials for the chemical industry,” said Chen Chunlong, a professor at the University of Washington in Seattle.
Scientists plan to create new versions of peroxidases that will be distinguished by an increased level of activity and will be suitable for industrial use soon.