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structure of the plastic-degrading ideonella sakaiensis mhetase bound to a substrate - polyethylene terephthalate properties

by:Cailong     2019-07-29
structure of the plastic-degrading  ideonella sakaiensis  mhetase bound to a substrate  -  polyethylene terephthalate properties
Extreme Durability of Pet (PET)
Debris makes it a long time.
Environmental burden.
At the same time, there is still a lack of sustainability in the current recycling efforts.
Two bacterial enzymes recently discovered that can specifically degrade PET are a promising solution.
First of all, sakaiensis PETase is a plant with good structure.
Characterize consensus α/β-
Hydrolysis folding enzyme to convert PET into single(2-hydroxyethyl)terephthalate (MHET).
MHETase, the second key enzyme, is the hydrolysis of MHET pet educts PTA and ethylene glycol.
Here we report the crystal structure of the active ligand
Free MHETase and MHETase are bound to a nonhydrolyzable MHET simulation.
MHETase has a classic α/β-structure, which is reminiscent of a Wei Che.
Hydrolysis domains and lid domains that give substrate specificity.
From a structural point of view
Mapping based on active site, activity analysis, mutation study, and first structure
Guiding changes of substrate specificity to bis(2-hydroxyethyl)terephthalate (BHET)
It is reported that we expect MHETase to be a valuable resource for further promoting the degradation of enzyme-promoted plastics.
Industrial production of PET began soon after its discovery and gradually increased, with an estimated 70 million tons in 2020.
One of the biggest advantages of PET is its chemical inertia due to the solubility of pta (TPA)
Make it almost resistant to environmental degradation.
Although PET and other synthetic polymer plastics are considered non-toxic, their larger particles and particles are persistent, ubiquitous in marine or terrestrial habitats and accumulate in organisms.
Often, they are also carriers of potentially toxic pigments and additives.
The current recycling efforts cover only a small part of PET waste and reduce the production of low-value products.
They depend on the addition of a large number of raw polymers and the heavy consumption of energy.
Alternatively, it has been determined that several enzymes can hydrolysis PET to TPA and ethylene glycol at high temperatures, although the activity is low.
Biotechnology Enzyme optimization has been successful to some extent, but so far has not led to the production of enzymes, which can be at cost-
Effective and eco-friendly way.
Recently, bacteria 201-
F6 was found and displayed at low
The Crystal of PET film. Two α/β-
Hydrolysis folding enzyme (α/β-hydrolases)
Pet ase and MHETase co-degrade PET through MHET two steps to produce TPA and ethylene glycol-
Building blocks required for a new round of PET synthesis (Fig. ).
The latest crystal structure of PETase bound with ligand confirms the predicted α/β-
Enzyme folding, clarifying substrate binding, catalytic pattern, and even allowing enhancement of catalytic performance or change of substrate specificity.
Compared to known pets
On PET with ambient temperature and high crystal height, the activity of degradation enzyme, PETase is higher.
In contrast, the structure of the second enzyme MHETase
Essential for overall PET degradation
I don't know yet.
MHETase was originally assigned to the tannase enzyme family, which belongs to α/β-
Hydrolysis folding enzymes classified in the Hydrolase database.
The family consists of fungi and bacterial tannins enzymes and Wei.
Other significantly different bacterial leather enzymes can be found in different Block H (Tannases_bact)
In this database
For a long time, MHETase has been shown to only hydrolysis MHET without hydrolysis of BHET, PET-nitrophenyl (pNP)
Fatty ester or aromatic ester compounds transformed by other enzymes in the leather enzyme family, such as gallate acetate and ferulate acetate, indicate a highly restricted substrate specificity. All plastic-
Degradation enzymes known to date show α/β-hydrolase fold.
However, MHETase may have an unprecedented plastic bracket
Degradation enzyme.
In order to improve the catalytic action and expand the substrate specificity, thus significantly promoting the degradation of enzyme-promoted plastic polymers, this can be used.
Here, we show the crystal structure of PETase, MHETase, and MHETase bound with non-hydrolysis substrate analogs (MHETA)
Or benzene acid. A structure-
The underlying map of the activity site was plotted by mutation and binding studies with different substrates, used to determine the molecular basis of product inhibition, and to guide mhetase variants with enhanced MHET activity and even changing substrate specificity to BHET.
We expect our data to greatly facilitate the current understanding of enzymes that degrade synthetic polyester.
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