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PET-ase mutant enzyme degrades plastic at super-speed


Chemists at the University of Portsmouth in southern England have isolated an enzyme capable of breaking up PET molecules.

A bacterial enzyme, which is an organic microorganism made of protein combinations, could provide a cheap and fast solution for plastic waste recycling, as well as depleting mountains of PET lying in landfill around the world.

The bacterium, Ideonella sakaiensis 201-F6, was found by chance feeding on waste from an industrial PET recycling facility. PET has only been widely used since the 1970s, so the bacterium had evolved at breakneck speed to use the new food source.

Ideonella sakaiensis 201-F6 was found to use a specially evolved enzyme, now known as PETase, to transfer to carbon for energy.

Professor John McGeehan, leader of the trials with PETase enzymes at the University of Portsmouth.

By using a super-advanced microscope, based at the Diamond Light Source in Oxfordshire, UK, the Portsmouth scientists, along with the National Renewable Energy Laboratory in Colorado, the University of South Florida, and the University of Campinas in Sao Paulo, Brazil could look at the three-dimensional make-up of PETase at an extremely high resolution using the Long-Wavelength Macromolecular Crystallography beamline.

Prof Andrew Harrison, CEO of Diamond, told the journal PNAS: “The detail that the team were able to draw out from the results achieved on the I23 beamline at Diamond will be invaluable in looking to tailor the enzyme for use in large-scale industrial recycling processes. The impact of such an innovative solution to plastic waste would be global. It is fantastic that UK scientists and facilities are helping to lead the way.”

PETase could be derived from naturally occurring cutinase, but with a larger active site cleft (the area where an enzyme locks to a molecule) to connect to bulkier PET parts.

 The bio-based PEF can also be eaten by the enzyme.

Last year, Cambridge researchers found that the waxworm caterpillar can break up PET, and the University of Cambridge’s Department of Biochemistry has discovered the larvae can also break up polyethylene bags.

ar©tur 2016