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Every two seconds, an American needs a blood transfusion. But blood transfusions are not as simple as taking one person's blood and giving it to another. There are four different types, but type-O negative blood is the only one that can be given to people of all other types. Because of this "universal" quality, it is rare and in high demand, but an incredible breakthrough announced on Monday could change that.
In Microbiology of nature, a new article presents a viable way of converting blood type A to blood O using enzymes from the intestinal bacteria Flavonifractor plautii. When these enzymes are added to type A blood, the molecules on its surface that define it as type A become unattached, turning it into universal type O blood. This is very useful, since type A positive blood is the second most common type in America, while only 7% are universal type O negative donors.
I became aware of the potential for blood conversion if we could find specifically active and active enzymes. "
Stephen Withers, Ph.D., Head of the Study Team, Professor of Chemistry at the University of British Columbia, tells the story reverse that this study marks the closest time scientists have been able to convert blood types. The possibility of using enzymes to do this was first demonstrated in 1982 for type B blood (which is easier to convert), but it required huge amounts of enzymes for this to happen. In 2007, scientists discovered that two bacterial enzymes could also eliminate antigens A and B, but, as Withers explains, "they were still not sufficiently effective or selective and did not work in the blood. total". To make it a viable method, he should find a way to make enzymes more efficient.
Withers' research has always focused on enzymes that can assemble and degrade complex molecules called glycans, such as sugars on the surface of cells.
"During conversations with colleagues at the Center for Blood Research at the University of British Columbia, I realized the potential for blood conversion if we could find enzymes that were sufficiently active and specific," Withers explains.
The team discovered the good enzymes in bacterial DNA from human stool. Previous research has suggested finding genes for mucin-digesting enzymes, proteins similar to sugars found in red blood cells. By using this DNA to develop these enzymes Escherichia coli revealed that some enzymes could, in fact, eliminate A antigens in human blood, turning them into O-negative blood.
The team is now starting safety tests in collaboration with experts from Canadian Blood Services, a non-profit organization for blood collection, to ensure that converted red blood cells are completely safe. and functional.
Security, safety and security issues are the top three priorities on the agenda. "
"The things we need to worry about are if all of the A antigen has been removed and if the enzyme has caused other changes to the surface of the red blood cells," Withers said.
They do not think it happened – but they have to prove it. Mr. Withers hopes that the "test tube" phase will be completed within two years ("if we get the funding we need"), and that the clinical trials will take a few more years. All this assuming that no problem arises.
"Security, safety and security issues are the top three priorities on the agenda," said Withers.
If everything works, it could revolutionize blood donation by making huge amounts of O blood available. According to the American Red Cross, only 3 in 100 Americans donate blood. When a blood group is sold, all those who need it suffer. There is always a need for blood – especially of the type that everyone can use.
Abstract:
Access to efficient enzymes capable of converting type A and B red blood cells to "universal" O donors would greatly increase the blood supply for transfusions. We report here the functional metagenomic screening of the human intestinal microbiome for enzymes capable of eliminating related sugar antigens of types A and B. Among the genes encoded in our library of 19,500 expressed fosmids carrying the bacterial DNA of In the intestine, we identify a pair of enzymes from the obligate Flavonifractor plautii that work together to effectively convert the A antigen into O-type blood H antigen via an intermediate galactosamine. . The X-ray structure of N-acetylgalactosamine deacetylase reveals the active site and mechanism of the founder member of the esterase family. Galactosaminidase extends activities within the CAZy GH36 family. Their ability to completely convert A to O from the same rhesus type to very low levels of whole blood enzymes will simplify their incorporation into the practice of blood transfusion, thereby expanding the blood supply.
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