AP Biology class blog for discussing current research in Biology

Tag: plastic

Can Enzymes Be the Solution to the Single-use Plastic Pollution Crisis?

Single-use plastic pollution, a massive issue that has been harming our planet’s environmental health for decades, might be able to be tackled with something as small as an enzyme.

Researchers Jen Dubois of Montana State University and John McGeehan of the University of Portsmouth have discovered enzymes that break down elements of single use plastic. These remarkable microbiological tools, called PETase and MHETase, have the ability to breakdown terephthalate polyethylene—one of the building blocks of (PET) plastic. 

So, how does it work? How do these enzymes essentially eat plastic?                       PET is a polymer, which is a mega-protein made up of many smaller molecules (monomers). With the help of PETase and MHETase, these enzymes break the plastic down into “chemical building blocks”: ethylene glycol (EG) and TPA. Evidently now, a problem arises that concerns where these byproducts of the enzyme’s activity can go next. Thankfully, EG is a product that is useful for many everyday items, such as being an ingredient in antifreeze solution used in cars. But researchers can’t tell the same story for TPA; There is essentially no use for a chemical like this outside of PET plastic. So, with inspiration from the mechanism that made this byproduct in the first place, the Portsmouth research team thought the creation or discovery of another enzyme could do the job of breaking down TPA in the same way as for PET plastic.

Researchers from Michigan State University did just that, and found a solution to the overwhelming amount of TPA byproduct from PETase/MHETase activity of breaking down PET plastic. TPADO, an enzyme that breaks down TPA byproducts, was introduced, and was soon found to have incredibly binding ability to TPA—so much so that its fit into the chemical is described as “a hand in a glove.” In other words, the active site, the groove on the surface of the TPADO enzyme, fits perfectly with its substrate, TPA, by matching its exact shape, charge, and type of relationship with water (either hydrophobic or hydrophilic). 

This groundbreaking research due to the collaboration of many researchers across several universities has revealed the long awaited light at the end of a very dark tunnel environmentalists call ‘the plastic crisis.’ With around 400 million tons of plastic discarded and then scoured all over the earth every year, the human race produces a weight of single-use plastic trash that is almost equivalent to the mass of the whole human population. But, with enzymes like PETase, MHETase, and now TPADO, modern science is now able to convert plastic waste into valuable molecular ingredients for other products, essentially minimizing waste in not only the plastic industry, but others, as well. 

Still, these researchers’ jobs are not done, and they know it. TPADO has been tested under powerful x-rays to show its exact shape and molecular structure and reveal its innerworkings. With information like this, the world of enzyme engineering can be improved to make artificial ones that are more efficient and more useful. 

So, something as small as enzymes can be the solution to the single-use plastic crisis we have here on planet earth? The answer is ‘yes’, thanks to modern science and dedicated researchers at the universities of Montana, Portsmouth, and Michigan State.

Plastic bottles for recycling

Image of single-use plastic waste.

This New Enzyme Could Save Your Future

According to a study done by Professor John McGeehan, the Director of the Center for Enzyme Innovation at the University of Portsmouth, and Dr. Gregg Beckham, a Senior Research Fellow at the National Renewable Energy Laboratory, a new enzyme has been manufactured that can break down trash at rapid speeds and with great effectiveness.

In previous years, scientists discovered and worked on PETase, an enzyme that breaks down PET, a material needed to produce lots of one-time-use plastic items. PETase can break down PET, which stands for polyethylene terephthalate, since the enzyme returns the molecule to its monomer form through depolymerization, a process meant to convert polymers into monomers by increasing the levels of thermal energy. PETase transformed the process of breaking down plastic by being able to do what nature can in 100 plus years in only a few days. As we have learned in our AP Biology class this year, breaking down polymers into monomers is an important process of life. Whether it takes place in our digestive system or in attempts to recycle trash, depolymerization essentially is one aspect of biology that allows life to take place.

Inspired to do more research because of the success with PEtase, the same group of scientists has discovered MHETase, another enzyme that helps to break down waste through the same process as PETase. As we know from class, an enzyme is a typ of protein that speeds up chemical reactions. So when they combined PETase with MHETase, PET was broken down in half of the time that it took PETase alone to break down PET. After that, the scientists physically constructed bonds between PETase and MEHtase by using a microscopic X-ray system in order to be able to see at such a molecular level, and the process of breaking down PET became three times more efficient than when the PETase and the MEHtase were simply just mixed together. This new combination of PETase and MEHtase is commonly referred to as a “super-enzyme” or the enzyme “cocktail”. 

Not only do PETase and MEHtase work well together since they both break down PET, but they both break down PET through different strategies. Together, PETase and MEHtase help to quickly and effectively return the PET to its original, monomer form. Separately, PETase will deconstruct the surface of the PET molecules, while MEHtase will help deconstruct the molecule in its entirety. As a team, PETase and MEHtase will allow for the plastic items containing PET to be recycled and reused, breaking the cycle of disposing of plastics and the initiation of factories to make more. 

As waste truly begins to pile up on Earth, a “super-enzyme” like PETase with MEHtase certainly gives all people some hope for the future of our planet. The whole decomposition process can be made so much faster and so much more efficient with the new enzyme “cocktail”, and hopefully, the production of plastic and PET slows due to this new, groundbreaking discovery. Let us all think upon the effects that this super-enzyme can have; what will be your next steps towards a waste-reduced planet?

The Microwave. Cancer Causer? Or Convenient Cooking Appliance?

What is the Microwave?

So I’ll assume you all know what a microwave generally is. That black white or silver box on your kitchen counter that heats up your pasta at 1am. Letting you know its done with an alarm that’s far too loud. But what is it actually? How does it work? As stated in the first paragraph of this article, the discovery of the microwave was just an accident. The Microwaves emitted by various pieces of equipment were enough to heat foods and in the case of the story from the article, melt the scientist’s snack. The production of the microwave blew the minds of many. Providing a quick and easy way to near-instantly heat your food.


How Could It Be Bad for You?

Throughout my life, my father has always told me not to stand directly in front of the microwave while it was on. No matter how much I liked watching my snack spin and spin and spin in the magical machine, the thoughts of the horrifying radiation hurting me overtime was enough to deter me. But it is, in fact, untrue that microwaves cause cancer or any type of injury/illness due to its radiation. The device would need to be putting out much higher frequency wavelengths, not the microwaves that your microwave lets leak out through the door.




(Wave Structure) 

Is Your Microwave Killing You?

No, the answer is most likely no. More of the issue is what you are putting into the microwave. Putting metal in the microwave can be a terrible idea. Speaking from experience I’ve seen silverware spark in the microwave. Depending on the type of silverware and variety of utensil it may not go as poorly but never the less is a bad idea to try. Also, many sources suggest against putting plastic into the microwave just because of the interaction high heat and soft plastic can have together. As well as possibly melting, there is some interesting research to see if the heat will cause chemicals to leach into your food. Something that only sounds like a bad thing for human health. So is your microwave killing you? Most likely not, just use some common sense when reheating your leftovers in the middle of the night.

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