Enzyme in Human Gut May Convert A and B Blood Types to Universal O

The sugar-removing enzyme may lessen the demand for universal blood donors.

In January, the Red Cross urged the public to donate blood after severe weather resulted in hundreds of cancelled blood drives. Blood banks are always looking for O-type donations, especially for emergency use since it is the only blood type that can be universally received. However, a recent finding may help lessen the increasing demand for O-type blood.

Researchers discovered an enzyme found in the gastrointestinal (GI) tract that can efficiently convert A- and B- blood into O-type blood, according to a study published by the American Chemical Society.

"We have been particularly interested in enzymes that allow us to remove the A or B antigens from red blood cells," study author Stephen Withers, PhD, said in a press release. "If you can remove those antigens, which are just simple sugars, then you can convert A or B to O blood."

Previous research has attempted to find a practical way to alter blood type, but findings have not been efficient, safe, or cost-effective for widespread use. This time, researchers turned to metagenomics to search enzymes for sugar residues, according to the study.

"With metagenomics, you take all of the organisms from an environment and extract the sum total DNA of those organisms all mixed up together," Dr Withers said. "This is a way of getting that genetic information out of the environment and into the laboratory setting and then screening for the activity we are interested in.”

The research team was able to efficiently search millions of microorganisms and then use E. Coli to discover genes with DNA coding that allow enzymes to bind with sugar. Mosquitos and leeches were initially considered for the study due to their ability to alter blood, however, an enzyme found in the human GI tract ended up being the most successful match, according to the study.

The enzymes, known as mucins, are essentially sugar-coated glycosylated proteins that gut bacteria can easily attach to and feed off to regulate digestion. Mucin sugars can sometimes resemble A- and B- antigens, according to the study. Researchers looked even closer at the enzyme that removes sugar from mucin, and found this enzyme family to be 30 times more efficient in removing red blood cell antigens than those found in previous research.

Moving forward, the research team plans to confirm these results through further analysis, study the enzyme on a larger scale, and use technology that stimulates natural evolution to create sugar-removing enzymes that could work even more quickly.

"I am optimistic that we have a very interesting candidate to adjust donated blood to a common type," Dr Withers concluded. "Of course, it will have to go through lots of clinical trials to make sure that it doesn't have any adverse consequences, but it is looking very promising."