PROCESSORS

RICHLAND, Wash.—Scientists at the Department of Energy's Pacific Northwest National Laboratory have successfully immobilized enzymes while simultaneously enhancing their activity and stability, opening up new possibilities for using tailored nanoporous materials. findings, reported in an upcoming issue of the Journal of the American Chemical Society (available online Aug. 28), could enable the development of novel sensor and decontamination systems for homeland security, environmental protection and energy generation as well as new industrial chemicals and separations.

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"For decades, scientists have been searching for ways to immobilize soluble enzymes with a variety of solid materials. But the results have been disappointing because only small amounts of the immobilized enzymes show any biological activity," said Eric Ackerman, PNNL molecular biologist. "For the first time, we have immobilized an enzyme at high concentrations in a way that actually enhances its stability and activity." In lab tests, PNNL scientists nearly doubled the activity levels of an enzyme called organophosphorus hydrolase, known for its potential for biosensing and decontaminating poisonous agents. "By using different highly active and stable immobilized enzymes, we could potentially make enzymatic systems to inactivate certain chemicals or bioweapons, thus serving as a protective barrier in air filtration systems," said Ackerman. Fabrication of a more stable and active enzyme delivery method could potentially benefit other industries as well. For example, food processing companies use natural enzymes to produce items such as cheese, beer and soft drinks, while the biomedical industry uses them to manufacture drugs. Enzymes, which are proteins found in all organisms from humans to viruses, function as catalysts. Increasing an enzyme's activity—while enhancing enzyme stability—could facilitate more efficient chemical processes. To achieve enhanced stability and activity, scientists modified existing nanoporous silica originally developed at PNNL to sequester mercury for environmental remediation. This material, called SAMMS—for Self-Assembled Monolayers on Mesoporous Supports—contains uniform pores that can be prepared with a variety of pore sizes according to the application. In this case, researchers enlarged the pores to 30 nanometers, which is a size sufficiently spacious to accommodate the immobilized enzymes. Then, the pore surfaces were coated with a specific chemical compound to provide an optimal environment for enzyme activity and stability. Image Caption: PNNL scientists have created a nanoporous silica that increases enzyme activity and stability by binding part of an enzyme to the walls of a 30-nanometer pore.