Single-atom substitution boosts PET-degrading enzyme efficiency
Researchers at the Australian National University altered a single atom in PET-degrading enzymes by replacing tryptophan with azatryptophan. This change nearly doubled the enzymes' ability to break down PET plastic while preserving their thermal stability. The finding suggests that precise atomic modifications can overcome the usual trade-off between enzyme activity and stability.
The azatryptophan substitution swaps a carbon-hydrogen group for a nitrogen atom at one position in the enzyme's structure. This isosteric change preserves the protein's overall shape while altering its electronic characteristics, allowing the enzyme to process PET nearly twice as quickly without losing heat tolerance. The work appears in Angewandte Chemie International Edition.
The PETra assay addresses a practical bottleneck in enzyme research. Because PET resists dissolution and has complex structure, conventional activity measurements require hours or days. PETra employs a soluble fluorescent stand-in that yields results within minutes, and its readings track closely with actual solid PET breakdown. This rapid screening capability could accelerate testing of future enzyme variants.
If single-atom enzyme modifications prove scalable, plastic recycling operations could eventually adopt biological breakdown as a viable complement to mechanical methods. The PETra screening tool may also shorten development cycles for enzyme engineers across industries, potentially lowering costs for sustainable manufacturing and biotechnology applications. However, laboratory efficiency gains do not guarantee commercial viability; factors such as production costs, reaction conditions, and infrastructure requirements will determine whether this approach moves beyond research settings.