Gut bacteria enzyme turns other blood types into type-O

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The four major blood groups (A, B, AB, O) are determined by the presence or absence of two antigens – A and B – on the surface of red blood cells. When either A or B antigen are present on the surface of RBC’s, the resultant blood type is A group or B group, and the presence of both or its absence makes it AB group or O group respectively.

Credit: www.biotechinasia.com

Type O blood is always in high demand and short supply because it is the universal blood type that is preferred for emergency transfusions as they do not cause any bad mismatch reactions.

Scientists have always pursued the idea of converting donated blood to a common type like “O” group for a while, but they have yet to find efficient, selective enzymes that are also safe and economical.

Now, scientists say they have identified enzymes — from the human gut — that can turn type A and B blood into O, as much as 30 times more efficiently than previously studied enzymes.

“We have been particularly interested in enzymes that allow us to remove the A or B antigens from red blood cells,” Stephen Withers, Ph.D. at the University of British Columbia (UBC), says. “If you can remove those antigens, which are just simple sugars, then you can convert A or B to O blood.”

By using metagenomics, the researchers screened the genes of millions of microorganisms and found a successful candidate enzyme in the human gut microbiome, that could help cleave sugar residues.

Our gut wall is lined with glycosylated proteins called mucins, that provide sugars which serve as attachment points for gut bacteria. Some of the mucin sugars are similar in structure to the antigens on A- and B-type blood.

The researchers homed in on the enzymes the bacteria use to pluck the sugars off mucin and found a new family of enzymes that are 30 times more effective at removing red blood cell antigens than previously reported candidates.

“I am optimistic that we have a very interesting candidate to adjust donated blood to a common type,” Withers says. “Of course, it will have to go through lots of clinical trails to make sure that it doesn’t have any adverse consequences, but it is looking very promising.”

Withers is now working with colleagues at the Centre for Blood Research at UBC for validating these enzymes and testing on a larger scale for potential clinical testing.