An enzyme is found in the human intestine that turns type A blood into type O and allows transfusion to anyone
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The blood type a person has to exist, such as type A · B type · O type · AB type, but in the case of a blood transfusion, you must select a blood type compatible with the patient, O type ' to anyone transfusion It is known to be capable of 'blood type' and may be transfused as an alternative to other blood types in emergency situations. Researchers at the University of British Columbia discovered a combination of enzymes that convert type A blood to type O and announced that 'the production of universal blood has made a big step forward.'
An enzymatic pathway in the human gut microbiome that converts A to universal O type blood | Nature Microbiology
https://www.nature.com/articles/s41564-019-0469-7
Type A blood converted to universal donor blood with help from bacterial enzymes | Science | AAAS
https://www.sciencemag.org/news/20019/06/type-blood-converted-universal-donor-blood-help-bacterial-enzymes
In the United States, it seems that as many as 16,500 liters of blood are transfused every day, including regular surgery, emergency surgery, and regular blood transfusion. However, the blood to be transfused must be compatible with the patient's blood type, and transfusion of blood of the wrong blood type can be fatal.
On the surface of red blood cells contained in the blood, there are sugar molecules consisting of chain-like sugars called A / B antigens, and their blood types are classified according to the difference in the end of this sugar molecule . When a person of type A gets transfused with type B blood, the immune system attacks an antigen different from the original blood antigen.
However, since there is no A / B antigen in type O blood, transfusion into patients of different blood types will not be attacked by the immune system. Therefore, Type O is considered to be a universal blood that can be transfused to patients of any blood type, and it is useful for emergency surgery etc. when there is a lack of compatible blood. Based on this idea, scientists have continued researching, 'Can we create universal blood by removing antigens that evoke an immune response from the blood?'
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In the past, attempts have been made to remove type A antigens, the second most common type of blood, and convert type A blood to universal blood. However, known enzymes that can remove sugar molecules from the surface of red blood cells have not produced results that are economically efficient.
So the research team led by Steven Wizards, a chemical biologist at the University of British Columbia, decided to look for more effective enzymes in human intestinal bacteria. Some enteric bacteria stick to the intestinal wall, and there are types that eat a mixture of sugar-rich glycoproteins and mucins . Mucin's sugar molecule seems to be similar to the type A antigen on the surface of red blood cells, which is the deciding factor in blood group classification.
The research team separates the DNA of microorganisms that eat such mucins from human stool samples. If the DNA code containing mucin degrading enzyme is cut out and incorporated into E. coli widely used in experiments, whether any E. coli produces a protein that degrades the sugar molecule of type A antigen similar to mucin The researchers monitored.
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Initially, it was thought that this experiment had failed. However, when two enzyme DNAs that degrade mucin obtained from the enterobacteria named Flavonifractor plautii were tested at the same time, it was found that the sugar molecule of the antigen was immediately removed. Even in human blood, it has been confirmed that sugar molecules can be removed simply by adding a small amount of degrading enzyme into blood of type A.
If this enzyme becomes widely available, type A, which is a large part of blood for transfusion, can be converted to universal blood, and it is thought that the problem of inadequate blood compatibility will be greatly alleviated. On the other hand, Wizards will study in future work how to confirm whether the combination of enzymes discovered this time has not been removed to the essential one on the surface of red blood cells, or sure to remove all type A antigens in blood. Pointed out that it is necessary to establish It seems that it is still necessary to overcome some obstacles for commercialization.
by Chris Gladis
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