The Enzyme Toolbox—Alternatives to PETase for Microplastic Breakdown

  • Cutinases, MHETases, carboxylesterases, and lipases expand substrate scope.
  • Fusion proteins (CBMs) and hybrids enhance surface binding and catalytic rates.
  • Genome mining discovers new enzymes from extreme environments.
  • Multi-enzyme approaches optimize efficacy for diverse plastics.
  • Greater enzyme diversity strengthens prospects for medical microplastic removal.
  1. Current advances in the structural biology and molecular engineering of PETase (2023)
  2. PETase serum paper (2024)
  3. PET hydrolases and alternatives overview (2022)
  4. Advances in MHETase structure/function (2024)
  5. Characterization of PETase from marine sponge (2017)

The fight against microplastics extends beyond PETase. Cutinases, carboxylesterases, lipases, and MHETases provide expanded substrate flexibility and catalytic power. Cutinases, like Cut190 and LCC, operate robustly under diverse industrial conditions and degrade polyesters, including PET. MHETase complements PETase by breaking down its intermediate product, MHET, into benign monomers, completing the depolymerization pathway.

Enzyme hybrids and fusion proteins introduce carbohydrate-binding modules (CBMs) or hydrophobins, enhancing substrate recognition and surface affinity. Genome mining continues to uncover new variants from environmental and marine sources, broadening the arsenal for plastic degradation. These alternative or synergistic enzymes could be customized for specific therapeutic needs, considering the types and prevalence of microplastics found in the human body.

For medical applications, selecting the right mix of enzymes—for example, combining PETase with cutinase or engineering multi-functional fusions—improves efficiency against the complex cocktail of microplastics present in serum and organs. Engineered variants promise broader coverage and improved safety profiles.