March 25, 2008

Molecular Computation

Control System With An Enzyme PIN

Flexible network processes chemical information

Carmen Drahl

A security-type control system with a password made up of enzymes rather than numbers or letters has been devised by Evgeny Katz and coworkers at Clarkson University in Potsdam, N.Y. This type of biochemical network, which mimics an electronic keypad lock, could one day be used to control implantable medical devices based on individual body chemistry (J. Am. Chem. Soc., DOI: 10.1021/ja7114713).

CODE An enzyme-based security-type keypad begins with a solution of sucrose, a dye, and oxygen. The password consists of three enzymes (blue, yellow, and red) that must be added to the solution in the right order. The correct combination oxidizes the dye to a colored product, a measurable output.

Another research group has already made this type of chemical device from a pathway that manipulates synthetic fluorophores (J. Am. Chem. Soc. 2007, 129, 347). However, the new system is made from biochemical components, so it "offers advantages in terms of biocompatibility," says molecular electronics expert Devens Gust of Arizona State University. It is also highly adaptable; enzymes or substrates can be changed for different applications, Katz tells C&EN.

To demonstrate the system, Katz's team developed a sucrose solution containing a dye that would yield a colored output after a sequence of three enzymes is added to it. The first enzyme, invertase, hydrolyzes sucrose to glucose and fructose. The next enzyme oxidizes glucose while reducing oxygen to hydrogen peroxide. Finally, a peroxidase uses hydrogen peroxide to oxidize the dye to a measurable colored product. No colored product is formed unless all three enzymes are added in the correct order.

It's too early to know whether this type of enzyme network may be used for making molecular-level decisions in the body, such as releasing a drug in response to a specific sequence of biochemical events, Katz says. For now, the team is working on reconfiguring enzyme networks to process biochemical information in different ways.

Chemical & Engineering News

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