Public Release: 

Better Peroxidase Improves Disease Diagnosis

Purdue University

WEST LAFAYETTE, Ind. -- When Purdue University geneticist Rick Vierling first looked for ways to add value to soybeans, he didn't expect that he could help doctors diagnose AIDS in China. But that's exactly where his research is leading.

In June, the Indiana Crop Improvement Association (ICIA) licensed the use of soybean peroxidase in medical diagnostic test kits to Enzymol International Inc., Columbus, Ohio, and to American Qualex, San Clemente, Calif.

In July, American Qualex will announce the use of soybean peroxidase-based compounds in new diagnostic kits at the annual meeting of the American Association of Clinical Chemistry in Atlanta, July 22-23. The company also plans to collaborate with diagnostic, biotechnology, life science and pharmaceutical companies to develop other products that use soybean peroxidase.

The soy enzyme replaces horseradish peroxidase, which is an integral part of kits designed to help diagnose a myriad of viral, bacterial and parasitic diseases, including AIDS and malaria. Standard kits lose effectiveness in about four months without refrigeration, according to industry sources. Vierling's preliminary research suggests that kits made with soybean peroxidase should last unrefrigerated for at least a year. Such kits will be very useful in places such as China, Africa and Central America, he says.

Vierling, director of the Genetics Laboratory for the ICIA, started experimenting with soybean peroxidase because it is a hot "green" industrial commodity that can be extracted from soybean seed coats. Vierling says researchers have found ways to extract peroxidase from the soybean hulls without reducing the value of the oil or the meal in the beans.

"Peroxidase replaces a lot of really harsh chemicals," says Alex Pokora, vice president for technology for Enzymol, a worldwide leader in developing peroxidase technology. "It's a cleaner technology, and it's cost effective."

Manufacturers became interested in soybean peroxidase because the supply of horseradish peroxidase was limited and the horseradish enzyme wasn't very stable at high temperatures. Researchers from Enzymol asked Vierling to test soybean peroxidase and to look for soybean varieties with a higher peroxidase content.

Vierling immediately confirmed that the soy enzyme worked better.

"All plants contain peroxidase, but not all peroxidase is created equal," Vierling says. "Soybean peroxidase is highly reactive and thermally stable. I don't think there's a better peroxidase out there."

As Vierling measured enzyme levels in beans, he saw that a quick, chemical test for peroxidase activity would greatly speed his research and plant breeding efforts. He developed one -- and in doing so, he noted that his technique was similar to medical diagnostic test kits that use horseradish peroxidase. He suspected that the medical kits might work better if they were made with the soy peroxidase. Preliminary tests confirmed his suspicions.

For further confirmation, Vierling sent samples of soybean peroxidase to John Morrow, a professor at Texas Tech University's Health Science Center in Lubbock, Texas. Morrow and Vierling had worked together when Vierling was a graduate student. Vierling asked Morrow to substitute soybean peroxidase for horseradish peroxidase in clinical diagnostic tests.

"I was lukewarm about the idea at first," says Morrow, "but when I tried it, I was converted. I think he's got something that's a nice improvement over current technology."

In addition to its superior performance in medical and industrial applications, soybean peroxidase is relatively easy to obtain. The beans are widely grown, and production, transportation and storage facilities already are in place to deliver high-peroxidase beans for enzyme extraction.


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