Enzyme Tweak Offers Plastic Waste Solution

Scientists have achieved a major breakthrough by swapping a single atom inside a plastic-degrading enzyme, doubling its efficiency without sacrificing thermal stability.

The study at the Australian National University (ANU) in Canberra, Australia, overcame a long-standing hurdle in enzyme engineering. Traditionally, using the 20 natural amino acids to make plastic-degrading enzymes break down polyethylene terephthalate (PET) faster, almost always causing them to unravel at high temperatures.

To bypass this trade-off, the ANU team introduced a synthetic amino acid called azatryptophan. Visually and chemically almost identical to the natural amino acid tryptophan, azatryptophan replaces a single carbon-hydrogen pair with a nitrogen atom. This atomic modification allowed the upgraded enzyme to degrade PET plastic in half the time while preserving its heat resistance.

Study lead, Dr. Elwy Abdelkader from the Research School of Chemistry, explained: “Instead of redesigning an enzyme with many mutations, we can make a very small, targeted change and have a significant effect on how it works.”

To accelerate their research, the team also created PETra, a new rapid fluorescence-based test that measures enzyme activity in minutes rather than days.

With over 350 million tons of PET plastic waste generated globally each year, this precise single-atom strategy offers a powerful new tool for combatting global pollution.

Additionally, co-author Professor Thomas Huber noted that expanding beyond nature’s 20 amino acids could soon help engineer hyper-efficient enzymes for new biofuels, sustainable manufacturing and medical applications.