# It Is Dangerous to Go Alone: Strategies to Optimize PET Biocatalysis and Upcycling through Enzymatic Synergism

## TL;DR

This review discusses how combining enzymes can improve the efficiency of breaking down PET plastic into reusable components.

## Contribution

The paper highlights novel enzymatic synergism strategies to enhance PET biocatalysis and upcycling.

## Key findings

- PET hydrolases are inhibited by intermediate reaction products like MHET.
- Synergistic enzyme cooperation can increase PET degradation efficiency and reduce costs.
- Combining enzymes enables full recovery of PET components for value-added chemical production.

## Abstract

Current mainstream
methods of plastic recycling are inadequate,
producing lower-quality polymers, or are cost-inefficient, requiring
expensive reagents operating under harsh conditions. Enzymatic biodegradation
of poly­(ethylene terephthalate) (PET) plastic was first extensively
described in 2005, and several PET degrading enzymes have been identified
since then. Recently discovered or developed PET-degrading enzymes
are inhibited by the intermediate reaction product, mono­(2-hydroxyethyl)
terephthalate (MHET). Therefore, the enzymatic conversion of PET into
its original components, terephthalic acid (TPA) and ethylene glycol
(EG), is still inefficient. The synergistic cooperation between PET
hydrolases and enzymes capable of hydrolyzing released intermediate
products can increase reaction efficiency, reduce separation costs,
and enable the full recovery of the basic components of PET for their
potential conversion into value-added chemicals. This review aims
to provide an overview of enzymes capable of degrading intermediate
products and potentially solving the heterogeneous product solution
problem, their structures and activities, importance, and potential
applications in combination with PET hydrolases.