ISU chemists have invented a new method of using enzymes that may someday clean up industrial waste.

Nenad Kostic, professor of chemistry, working with a grant from the United Soybean Board, developed a technique for encapsulating enzymes inside glass so that they are reusable for multiple reactions.

“The pores in glass are sufficiently large to allow a small molecule to penetrate, but sufficiently small to keep the large molecule locked in without any leakage,” Kostic said. “It’s like a cage in a zoo where large animals are inside, but birds can fly in and out.”

Kostic said enzymes are chemicals used to speed up chemical reactions.

“Each molecule of enzyme can process hundreds of thousands of molecules of its substrate per second,” he said.

“Dipping the glass in hydrogen peroxide will activate the enzyme, and then the active enzyme will convert small compounds into different compounds. This conversion is oxidation.”

Kostic said the enzymes, which are extracted from soybeans, could eventually be used to clean up industrial waste.

“In doing [this], we had an eye on a practical application. Many of the pollutants in industrial waste waters … contain these sulfur compounds which are noxious and toxic, so a method that would convert these sulfur compounds into a less toxic or innocuous product is needed,” he said.

Kostic did not work alone on the project, which began in 1996. Much of the help came from two graduate students in chemistry, Katya Kadnikova and Jovica Badjic.

Kadnikova said there are still many problems with the new technology.

“Even though the enzymes are quick, diffusion through the glass is time-consuming,” she said. Kadnikova said another problem is the catalysts can’t always be recycled indefinitely.

Kadnikova said Badjic was experimenting with the behavior of catalysts inside the glass, since it was discovered that their behavior is different from their behavior outside the glass.

Kadnikova is currently trying to apply the technology for use with other enzymes.

Although the initial research ended in 1998, Kostic said research is still being done to improve the technology.

“There are some fundamental scientific problems to be solved — how to optimize the activity of this enzyme, how to make full use of hydrogen peroxide and how to improve the efficiency of this process,” Kostic said.