A new family of enzymes has been designed to perform one of the most important steps in the transformation of plant waste into sustainable and high quality products such as nylon, plastics and chemicals.
The discovery was led by members of the same British and American enzyme teams who, last year, constructed and improved a plastic sealing enzyme, a potential breakthrough for recycling plastic waste. (Link)
The study, published in the journal Proceedings of the National Academy of Sciences was led by Professor Jen Dubois of Montana State University, Dr. Gregg Beckham of the US Department of Energy National Renewable Energy Laboratory (NREL), Professor Ken Houk at the University of California, Los Angeles along with Professor John McGeehan's Law at the University of Portsmouth.
The newly developed enzyme is active on the lignin of the major components of plants, which researchers have been trying for decades to find a way to break down effectively.
Professor McGeehan, Head of the Center for Enzyme Innovation at the School of Biological Sciences in Portsmouth, said: "This is our goal to discover enzymes from nature, bring them to our laboratories to understand how they work, then construct them for To produce new tools for the biotechnology industry, in this case we have taken a naturally occurring enzyme and designed it to perform a key reaction in the degradation of one of the toughest natural polymers.
"To protect its sugar-containing cellulose, plants have developed a fascinating complicated material called lignin that can only handle a small selection of fungi and bacteria. Lignin, however, represents a great potential source of sustainable chemicals, so if we can find a way to extract and use these building blocks, we can create good things. "
Lignin acts as scaffolding in plants and is central to water discharge. It provides strength and also defense against pathogens.
"It's a fantastic material," says Professor McGeehan, "cellulose and lignin are among the most abundant biopolymers on earth. The success of plants is largely due to the clear mixture of these polymers to create lignocellulose, a material that is challenging to melt. "
Current enzymes tend to work on only one of the building blocks of lignin, which makes the degradation process ineffective. With the help of advanced 3-D structural and biochemical techniques, the team has managed to change the form of the enzyme to accommodate several building blocks. To create new materials and chemicals such as nylon, bioplastic and even carbon fiber, from what has previously been a waste product.
The discovery also offers additional environmental benefits: Creating products from lignin reduces our dependence on oil to make everyday products and offers an attractive alternatives for burning it, which helps reduce carbon dioxide emissions.
The research team consisted of an international team of experts in structural biology, biochemistry, quantum chemistry and synthetic biology at the universities of Portsmouth, Montana State, Georgia, Kentucky and California and two US national laboratories, NREL and Oak Ridge.  Dan Hinchen, a doctoral student at the University of Portsmouth, said: "We used X-ray crystallography at Diamond Light Source synchrotron to solve ten enzyme structures in complex with lignin building blocks. This gave us the drawing to construct an enzyme to work on new molecules. lleagues were then able to transfer the DNA code for this new enzyme to an industrial strain of bacteria and expanded their ability to perform multiple reactions. "
Professor McGeehan said:" We now have principled principle that we can succeed with this class of enzymes to address some of the most challenging lignin-based molecules and we continue to develop biological tools that can transform waste into valuable and sustainable material. "
New "promiscuous" enzyme helps to transform plant waste into sustainable products
Melodie M. Machovina el al., "Activate microbial syringol transformation through structural-directed protein technology," PNAS (2019). www.pnas.org/cgi/doi/10.1073/pnas.1820001116
Engineering enzymes to turn plant waste into sustainable products (2019, June 24)
June 25, 2019
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