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Computational design of highly efficient thermostable MHET hydrolases and dual enzyme system for PET recycling

Authors :
Jun Zhang
Hongzhao Wang
Zhaorong Luo
Zhenwu Yang
Zixuan Zhang
Pengyu Wang
Mengyu Li
Yi Zhang
Yue Feng
Diannan Lu
Yushan Zhu
Source :
Communications Biology, Vol 6, Iss 1, Pp 1-18 (2023)
Publication Year :
2023
Publisher :
Nature Portfolio, 2023.

Abstract

Abstract Recently developed enzymes for the depolymerization of polyethylene terephthalate (PET) such as FAST-PETase and LCC-ICCG are inhibited by the intermediate PET product mono(2-hydroxyethyl) terephthalate (MHET). Consequently, the conversion of PET enzymatically into its constituent monomers terephthalic acid (TPA) and ethylene glycol (EG) is inefficient. In this study, a protein scaffold (1TQH) corresponding to a thermophilic carboxylesterase (Est30) was selected from the structural database and redesigned in silico. Among designs, a double variant KL-MHETase (I171K/G130L) with a similar protein melting temperature (67.58 °C) to that of the PET hydrolase FAST-PETase (67.80 °C) exhibited a 67-fold higher activity for MHET hydrolysis than FAST-PETase. A fused dual enzyme system comprising KL-MHETase and FAST-PETase exhibited a 2.6-fold faster PET depolymerization rate than FAST-PETase alone. Synergy increased the yield of TPA by 1.64 fold, and its purity in the released aromatic products reached 99.5%. In large reaction systems with 100 g/L substrate concentrations, the dual enzyme system KL36F achieved over 90% PET depolymerization into monomers, demonstrating its potential applicability in the industrial recycling of PET plastics. Therefore, a dual enzyme system can greatly reduce the reaction and separation cost for sustainable enzymatic PET recycling.

Subjects

Subjects :
Biology (General)
QH301-705.5

Details

Language :
English
ISSN :
23993642
Volume :
6
Issue :
1
Database :
Directory of Open Access Journals
Journal :
Communications Biology
Publication Type :
Academic Journal
Accession number :
edsdoj.6e3d9ac389e74090971cc7a410b1b230
Document Type :
article
Full Text :
https://doi.org/10.1038/s42003-023-05523-5