# Dynamic shift of internal electric field accelerates enzymatic polyethylene terephthalate depolymerization

## TL;DR

This study reveals how dynamic internal electric fields in enzymes help break down PET plastic more efficiently, offering a way to improve plastic recycling.

## Contribution

The discovery of dynamic internal electric fields stabilizing transition states during PET depolymerization is novel.

## Key findings

- PET chain binding and product release involve free energy barriers.
- The rate-determining step has a 20.4 kcal·mol⁻¹ free energy barrier.
- Dynamic internal electric fields lower the energy barrier by stabilizing the transition state.

## Abstract

Enzymatic recycling of polyethylene terephthalate (PET) has been recognized as an eco-friendly option for addressing the global plastic waste problem. Fully deciphering the catalytic mechanism is vital for designing high-performance enzymes. Here, we performed quantum mechanics/molecular mechanics molecular dynamics simulations to systematically explore the depolymerization mechanism of PET by the hydrolase LCCICCG. We demonstrate that both PET chain binding and product release require free energy barriers, whereas the rate-determining step corresponds to a catalytic process with a free energy barrier of 20.4 kcal·mol-1. We also observe that the enzyme internal electric field varies dynamically throughout the catalytic process. Oriented external electric field analysis indicates that this “dynamic shift” stabilizes the transition state more than the reactant, thereby lowering the energy barrier. We anticipate that these insights will contribute to the rational engineering of PET hydrolases by optimizing their dynamic internal electric fields.

Enzymes offer a sustainable solution for recycling polyethylene terephthalate (PET) waste, however, their efficiency remains limited for large-scale applications. Here, the authors use QM/MM MD simulations to reveal the depolymerization mechanism of a cutinase variant, uncovering dynamic internal electric fields that stabilize transition states and lower the energy barrier, offering a strategy to engineer high-performance PET hydrolases.