Enzymatic degradation of poly(ethylene terephthalate) (PET): Identifying the cause of the hypersensitive enzyme kinetic response to increased PET crystallinity

Thore Bach Thomsen, Tobias Radmer, Anne S. Meyer*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

19 Downloads (Pure)

Abstract

Plastic pollution poses a significant environmental challenge, with poly(ethylene terephthalate) (PET) being a major contributor due to its extensive use in single use applications such as plastic bottles and other packaging material. Enzymatic degradation of PET offers a promising solution for PET recycling, but the enzyme kinetics in relation to the degree of crystallinity (XC) of the PET substrate are poorly understood. In this study, we investigated the hypersensitive enzyme kinetic response on PET at XC from ∼8.5-12% at 50 °C using the benchmark PET hydrolysing enzyme LCCICCG. We observed a substantial reduction in the maximal enzymatic reaction rate (invVmax) with increasing XC, corresponding to a 3-fold reduction in invVmax when the XC of PET increased from 8.6% to 12.2%. The kinetic analysis revealed that the level of the Mobile Amorphous Fraction (XMAF), rather than XC, was a good descriptor for the enzymatic degradation rate response. By continuous monitoring of the enzymatic reaction progress, we quantified the lag phase prolongation in addition to the steady-state kinetic rates (vss) of the reactions and found that the duration of the lag phase was predicted from the vss and XC by multiple linear regression modeling. The linear correlation between the duration of the lag phase and the vss of the enzymatic PET degradation affirmed that the LCCICCG worked via a random/endo-type enzymatic attack pattern. The longer lag phase with increased XC of PET is proposed to be due to increased substrate entanglement density as well as unproductive enzyme binding to the crystalline regions of PET. The findings enhance our understanding of PET enzymatic degradation kinetics and its dependence on substrate composition, i.e., XMAF and XC.
Original languageEnglish
Article number110353
JournalEnzyme and Microbial Technology
Volume173
Number of pages7
ISSN0141-0229
DOIs
Publication statusPublished - 2024

Keywords

  • PET degrading enzymes
  • Poly(ethylene terephtalate)
  • Substrate crystallinity
  • Continuous assay
  • Mobile amorphous fraction

Fingerprint

Dive into the research topics of 'Enzymatic degradation of poly(ethylene terephthalate) (PET): Identifying the cause of the hypersensitive enzyme kinetic response to increased PET crystallinity'. Together they form a unique fingerprint.

Cite this