Adding to the difficulty is that once scientists isolate proteins by current methods, the process can destroy the proteins' biological activity. This renders them unusable for drug testing, for example, which is one of the main reasons scientists want to isolate proteins in the first place.
"Current methods essentially demand that we overhandle our proteins," Cooks said. "Just as you can ruin food's flavor by overhandling it while you cook, proteins can lose their reactivity to potential drugs by too violent an isolation process. Current methods do generate valuable data, but isolating and purifying thousands of proteins is costly in both time and money."
The solution Cooks' team devised was to separate the proteins in a single step using a mass spectrometer, an instrument chemists routinely use to analyze a sample of various materials by ionizing the sample's molecules and separating them in the gas phase so they can be detected individually. Cooks' team modified the spectrometer so it could collect the material after the separation by depositing the ions onto different locations on a chip's surface, a process called ion soft-landing. The comparatively gentle process produces highly pure protein samples that retain their ability to react with potential drugs.
"To continue the soup metaphor, our process allows you to separate the peas, carrots and potatoes from each other, while still allowing each to remain flavorful," Ouyang said. "People can use these separated, pure proteins to find out what function each performs for the body."
The chips themselves are a few centimeters square, and depositing proteins onto them takes a matter of hours. Once the surface is prepared, scientists expose it to a solution containing chemical or biological reagents that might r
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Contact: Chad Boutin
cboutin@purdue.edu
765-494-2081
Purdue University
14-Aug-2003