(Dieter Meyrl/iStock)

Every two seconds someone in the United States needs donated blood, the equivalent of more than 41,000 three-pint donations every day. There’s a perennial need for more donors — particularly donors of type O-negative blood, which doesn’t have the A- or B-type antigens that can provoke an immune reaction in some people. But fewer than 7 percent of Americans have O-negative blood.

In a new study published in the Journal of the American Chemical Society, researchers describe a way to transform A and B blood into a type that, like O, could be universally donated.

A team led by Stephen G. Withers of the University of British Columbia in Vancouver noted that blood type is determined by the presence of certain sugars, and scientists knew that those sugars could be removed by enzymes. But the natural enzymes were “inefficient,” not removing enough of the sugars.

Using an approach called “structure-guided directed evolution,” researchers channeled the mutations of one of these enzymes and created a version that improved its ability to remove the targeted sugars by 170-fold. “This is a significant step towards developing [methods] for the complete removal of blood group antigens,” the researchers write, “allowing for blood transfusions, and organ and tissue transplants from donors that would otherwise be mismatched.”