BIOTECHNOLOGY
Professor McGeehan and his team are now working on improving this enzyme for industrial-scale use , while continuing the search for new enzymes that can break down other highly polluting plastics .
The research is being facilitated by the Portsmouth researchers ’ access to the UK ’ s national synchrotron in Oxfordshire , called the Diamond Light Source . The synchrotron ’ s I23 beamline uses intense beams of X-rays 10 billion times brighter than the sun to act as a microscope
powerful enough to make individual atoms visible . It reveals the 3D structures of nature ’ s molecules of life , allowing researchers to apply the tools of protein engineering and directed evolution to continue to improve the PETase enzyme .
“ It allows us to see the 3D atomic structure of PETase in incredible detail ,” says Professor McGeehan .
“ Being able to see the inner workings of this biological catalyst provided us mixture of these polymers to create lignocellulose , a material that is challenging to digest .”
Current enzymes tend to work on only one of the building blocks of lignin , making the breakdown process inefficient . Using advanced 3D structural and biochemical techniques , the team has been able to alter the shape of the enzyme to accommodate multiple building blocks . The results provide a route to making new materials and chemicals such as nylon , bioplastics and even carbon fibre from what has previously been a waste product .
The discovery also offers additional environmental benefits – creating products from lignin reduces the world ’ s reliance on oil to make numerous everyday products and offers an attractive alternative to burning crop wastes , further helping to reduce CO 2 emissions .
The research team comprised international experts in structural biology , biochemistry , quantum chemistry and synthetic biology at the universities of Portsmouth , Montana State , Georgia , and California , and NREL .
The Diamond Light Source synchrotron was also again crucial . Dan Hinchen , a postgraduate student at the University of Portsmouth explains : “ We used X-ray crystallography at the synchrotron to solve 10 enzyme structures that were bound to lignin . This gave us the blueprint to engineer an enzyme to work on new molecules . Our colleagues were then able to transfer the DNA code for this new enzyme into an industrial strain of bacteria , extending the enzyme ’ s capability to perform multiple reactions .”
Professor McGeehan says the researchers now have proof of principle that this class of enzymes can be engineered to tackle some of the most challenging ligninbased molecules as a precursor to developing biological tools for converting waste into valuable and sustainable materials .”
PETase is a bacterial enzyme that breaks down PET plastic to monomeric molecules . The biological breakdown process yields terephthalic acid and ethylene glycol , which can be reused as an alternative to oil and gas feedstocks .
REVOLUTION PLASTICS / 2023 19