Using SAMDI mass spectrometry, the researchers separately tethered hundreds of different acetylated peptides to a gold-plated surface, then introduced lysate to see if a reaction would occur. When the reaction was complete, the plate was struck with a laser that released the peptides from the gold base. The contents of each site were weighed, allowing researchers to make an educated assumption about what occurred in each reaction.
"Until now, measuring the activity of enzymes in cell lysate has been a tremendous challenge because lysates contain tens of thousands of different molecules," Mrksich said. "With SAMDI mass spectrometry, we can use arrays having thousands of peptides to identify those many activities, and through sophisticated analysis we obtain a global picture of how complex cell functions are regulated."
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