Mutant enzyme can change any blood group to universal blood donor
There is a serious demand and supply problem when it comes to blood transfusions, and we all might be involved either in donating or receiving blood at some point of time in our lives. In general terms, blood transfusions require that the blood type of the donor match to that of the recipient. If they don’t belong to the same group, a patient can suffer serious side effects, and can even die. Only one group, such as type O, known as Universal donors can be transferred to anyone who is in need. This is because it doesn’t have the A or B antigens that could provoke an immune reaction inside the body.
The defining difference between A, B and O blood types is the presence of slightly different sugar structures on the outside of the red blood cells (RBC) of each type. Type A and B blood cells each have a single additional sugar attached to their surface. Since decades, researchers are looking for a way to convert types A and B into type O. They found that some enzymes from bacteria can clip the sugars off red blood cells that give blood its “type.” Until now the enzymes were not very efficient.
Canadian researchers, including one Indian origin scientist, Jayachandran Kizhakkedathu from the University of British Columbia along with Stephen G. Withers and colleagues recently published their interesting findings, titled “Toward Efficient Enzymes for the Generation of Universal Blood through Structure-Guided Directed Evolution” in the Journal of the American Chemical Society.
They have created an enzyme that could potentially solve this blood group conversion problem. The enzyme works by snipping off the sugars, also known as antigens, found in Type A and Type B blood, making it more like Type O.
To create this high-powered enzyme capable of snipping off sugars, researchers used a new technology called “directed evolution” that involves inserting mutations into the gene that codes for the enzyme, and selecting mutants that are more effective at cutting the antigens.
“We produced a mutant enzyme that is very efficient at cutting off the sugars in A and B blood, and is much more proficient at removing the subtypes of the A-antigen that the parent enzyme struggles with,” said David Kwan, the lead author of the study and a postdoctoral fellow. In just five generations, the enzyme became 170-fold more effective, according to their study.
“The concept is not new but until now we needed so much of the enzyme to make it work that it was impractical,” says Steve Withers, a professor in the Department of Chemistry. “Now I’m confident that we can take this a whole lot further.”
“The idea of converting blood types by enzymatic removal of blood group antigens using specific sugar hydrolysing enzymes (glycosidases) has been around since the early 1980s, but a major limitation has always been the efficiency of the enzymes that can do this: impractically large amounts of enzyme were needed,” he added.
However, these studies require some time until they reach clinical research settings. The Canadian Blood Services, the Canadian Institutes of Health Research, Health Canada and the Michael Smith Foundation for Health Research provided funding for this research.