Development of a highly active engineered PETase enzyme for polyester degradation

Polyethylene terephthalate ( PET ) accounts for ≈6% of global plastic production, contributing considerably to the global solid‐waste stream and environmental plastic pollution. Since the discovery of PET ‐depolymerizing enzymes, enzymatic PET recycling has been regarded as a promising method for plastic disposal, particularly in the context of a circular economy strategy. However, because the PET ‐degrading enzymes developed so far suffer from relatively limited thermostability and low catalytic efficiency, as well as degradation product inhibition, their large‐scale industrial applications are still largely hampered. To overcome these limitations, we engineered the current PET ‐hydrolyzing enzyme gold standard [the ICCG variant of leaf‐branch compost cutinase ( LCC ‐ ICCG )] using in silico protein design methods to develop a PET ‐hydrolyzing enzyme that features enhanced thermal stability and PET depolymerization activity. Our mutant, LCC ‐ ICCG ‐ C09 , features a 3.5 °C increase in melting temperature relative to the LCC ‐ ICCG enzyme. Under optimal reaction conditions (68 °C), the engineered enzyme hydrolyzes amorphous PET material into terephthalic acid ( TPA ) with a two‐fold higher efficiency compared to LCC ‐ ICCG . Owing to its enhanced properties, LCC ‐ ICCG ‐ C09 may be a promising candidate for future applications in industrial PET recycling processes.