Single Enzyme Nanoparticles Increase Catalyst Longevity for Months

To increase the longevity and versatility of enzymes, PNNL scientists have caged single enzymes to create a new class of catalysts called SENs (single enzyme nanoparticles). The nanostructure protects the catalyst, allowing it to remain active for five months instead of the normal life span of just a few hours.

Converting free enzymes into novel enzyme-containing nanoparticles can result in significantly more stable catalytic activity. Working in the William R. Wiley Environmental Molecular Sciences Laboratory, researchers modified a common protein-splitting enzyme called alphachymotrypsin to make it soluble, then added vinyl reagents to introduce the growth of molecular threads, or polymers, from the enzyme surface. A second polymerization step cross-linked the silicon chains, forming a basketball-netlike structure a few nanometers thick.

What results are SENs that appear in electron microscopic images as hollow enzyme-containing nanostructures about 8 nanometers across. The porous netting preserves the shape of the enzyme inside yet allows its active site to interact with a substrate. Among the uses for SENs is the breakdown of toxic waste, and use in many types of biosensors for national security applications.