science

MHETase

MHETase is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand MHETase rather than just read about it. In short: The enzyme MHETase is a hydrolase that cleaves 2-hydroxyethyl terephthalic acid to ethylene glycol and terephthalic acid. Discovered in 2016, this and the related enzyme PETase are used by the bacterium Ideonella sakaiensis to live on the plastic PET (polyethylene terephthalate) as sole carbon source.

Key takeaways

MHETase belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect MHETase to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of MHETase from memory before moving on to harder problems.

Reference excerpt

The enzyme MHETase is a hydrolase that cleaves 2-hydroxyethyl terephthalic acid to ethylene glycol and terephthalic acid. Discovered in 2016, this and the related enzyme PETase are used by the bacterium Ideonella sakaiensis to live on the plastic PET (polyethylene terephthalate) as sole carbon source. Since >80M tons of PET are produced annually, great interest has been shown in its biodegradation or recycling.

Chemical reaction The first enzyme of the PET degradation pathway, PETase, cleaves this plastic into the intermediates MHET (Mono-(2-hydroxyethyl)terephthalic acid) and minor amounts BHET (Bis-(2-hydroxyethyl)terephthalic acid). MHETase hydrolyses the ester bond of MHET forming terephthalic acid and ethylene glycol.

Besides its natural substrate MHET the chromogenic substrate MpNPT, mono-p-nitrophenyl-terephthalate, is also hydrolyzed well. This can be used to measure the enzymatic activity and determine the kinetic parameters. Ferulate and gallate esters, substrates of the closest relatives in the tannase family, are not converted. p-Nitrophenyl ester of aliphatic monocarboxylic acids like the widely used esterase substrate p-nitrophenyl acetate are not hydrolyzed either. The native enzyme is incapable of working on BHET, mono(2-hydroxyethyl)-isophthalate (MHEI), or mono(2-hydroxyethyl)-furanoate (MHEF). MHEI is a likely industrial PET degradation product due to the use of isophthalate comonomer. MHEF is a product of PEF degradation by PETase. Protein engineering research aims to overcome these barriers.

Structure The structure of MHETase was solved in 2019. It shows the common fold of the alpha/beta hydrolase superfamily. According to the classification in the ESTHER database, MHETase belongs to the family of tannases within block X. This family mainly contains tannases und feruloyl esterases. The enzyme consists of two domains: the hydrolase domain harbors the catalytic residues Ser225, His528 and Asp492; the lid domain contributes most of the residues of the substrate binding site.

External links ESTHER Datenbank

References

Illustrations

Worked examples

Example 1 — a first encounter with MHETase

Start with the simplest possible case. Write down what MHETase claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to MHETase before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about MHETase ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of MHETase

In research: MHETase appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses MHETase in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: MHETase is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hydrolases, so understanding it makes those chapters shorter.
In everyday life: Look for MHETase outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study MHETase in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what MHETase means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain MHETase out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is MHETase in simple terms?

Why does MHETase matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study MHETase?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on MHETase.