Tag Archives: enzyme engineering

The Future of Fighting Plastic Pollution : Enzymatic Plastic Breakdown

Plastic Pollution

With plastics being one of the most used materials for making many goods, it is no wonder that Canadians produce an estimated 3.3 million tonnes of plastic waste per year .Plastic pollution is an issue that has been present in the environmental community for some time now, as the effects of plastic pollution are far-reaching, even affecting tap water around the world, and harming marine wildlife through entanglement around the animal’s body. Some species like sea turtles eat the plastics, and this ends up blocking their digestive tract, resulting in starvation. This issue is not just restricted to turtles, and other animals such as whales also deal with this, as many whales have had large amounts of plastics found in them.  The video below by Kurzgesagt goes into the topic of plastic pollution more in-depth if you are interested in learning further about it.

 

Plastic Eating Bacteria & PET

Scientists had tried to combat this issue with a plastic-eating bacteria, that was initially found at a plastic recycling plant in Japan in 2016, but later on, when experimenting with the bacteria, the enzyme PETase was discovered. This enzyme works around twenty percent faster than the actual bacteria did at degrading PET, a very popular plastic used in many common items such as plastic bottles, and clothing. At the time, however, even PETase was not yet fast enough to be considered for widespread or commercial use.

Plastic Bottle Pollution in Armenia

Plastic Bottle Pollution in Armenia. Image: By UNDP in Europe and Central Asia

 

A Super Enzyme is Made

Recently, the same scientists who studied the PETase enzyme have made another improvement. In a new study, they show that by simply mixing PETase and MHETase (another enzyme) with one another, great improvements are made in the speed of PET degradation. After actually developing an enzyme from the PETase and MHETase to make a much stronger one, they developed an enzyme with PET breakdown that was three times faster than what they had previously achieved.

A diagram breakdown from the original PETase paper, with PET items being broken down by PETase and then further by MHETase. Source : https://www.pnas.org/content/115/19/E4350

Looking Forward

While the enzyme might still not be strong enough to combat global plastic pollution on a large enough scale, it does show how progress is slowly being made towards a safer and cleaner future. After finding the plastic-eating bacteria, improvements were implemented to create a faster enzyme, and then once again, making it even faster. The incremental gains in knowledge like these are what helps develop new technologies that help propel us further as species by combating issues in unique and innovative ways.

 

– Mehdi Mesbahnejad

Toward enzymatic blood conversion: A promising solution for blood shortage and transfusion incompatibility

What do you do when a patient requires blood transfusion, but the specific blood type is inadequate in the blood bank? Blood shortage has become a concern worldwide. According to American Red Cross, approximate 36,000 units of red blood cells (RBCs) are needed daily in the U.S, yet 13 million units are collected in a year, resulting in an average daily shortage of 400 units. And, this crisis usually expands during extraordinary situations. A recent example is the critical blood shortage during COVID-19 pandemic.

To solve the challenge, chemists have taken a step forward to examine the structure of RBCs and consider what if we convert all blood types to the universally accepted O blood. The importance of such research is that the barrier of blood transfusion between different types no longer exists. Hence, blood supply increases to ease the shortage.

What are blood types and transfusional barrier?

Image credit: InvictaHOG

There are four major blood types: A, B, AB, and O. Although blood might look the same and do the same job, such as carrying oxygen for respiration, transfusing incompatible blood type will trigger fatal immune responses. That is because of the additional sugar molecule, called antigen, attaching to the core sugar structure on a RBC. Type A blood has A antigens. Similarly, type B blood has B antigens. Moreover, type AB blood contains both A and B antigens. Importantly, type O has none of them.

Image credit: Marius Lixandru

Due to the presence of either A or B antigen, A-blood people cannot transfuse with type B; B-blood people cannot transfuse with type A. Consequently, AB-blood people cannot take either A or B but only with AB blood. Only O blood is the universally accepted type because it shares without being recognized as an outsider by our immune system.

Origin of enzymatic blood conversion

The first idea of blood-type conversion can be traced back to 1980s, Goldstein and his colleagues used an enzyme found in coffee beans and have shown success in the complete enzymatic removal of B antigen, generating non-antigen blood (O blood). However, the conversion requires large quantity of enzymes and output a trace amount of type O. As a result, the work done by Goldstein is not suitable for practical use. Similarly, other research uses an enzyme found in fungi to remove A antigen but its efficiency is still inadequate.

Improving enzyme activity using enzyme engineering

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Description: How enzymes found in gut bacteria change blood types for transfusion

Great improvement in enzyme activity is recently done by Kwan’s team who modify sugar hydrolase (GH98) with 170-times higher enzyme activity than that of the original hydrolase from human gut bacteria using enzyme engineering. It is inspiring because GH98 enzyme can remove both A and B antigens, whereas other enzymes used in past research only remove either A or B antigens. Their research broadens the specificity of the enzyme and makes the blood conversion more promising and practical for resolving blood shortage.

– Calvin Pan