Everett Lipman, a new assistant professor of physics at the University of California, Santa Barbara, recently co-authored an article in the journal Science, describing an innovative study of how to "see" proteins as they fold, the result of experiments performed with co-workers at the National Institutes of Health.
The machinery of life arises from interactions between protein molecules, whose functions depend on the three-dimensional shapes into which they fold, said Lipman. Although proteins are composed of just 20 different building blocks (the amino acids), the process by which a given sequence of these components adopts its unique structure is complex and poorly understood. Folding proteins are too small to view with a microscope, so the researchers used a method called Forster Resonance Energy Transfer, or FRET, to study them. Using a microfabricated silicon device and a microfluidic mixing technique, they were able to observe single protein molecules at various times after folding was triggered.
Two small molecules of fluorescent dye (red and green) were applied to amino acids in the protein. When the green dye was excited by a laser, it either emitted green light or transferred the energy to the red dye, causing it to light up. The green dye is a photon donor and the red dye is a photon acceptor. If the two dyes are close together,
more red is emitted as the energy is transferred easily to the red. If they are far apart, more green light is emitted. The fraction of red counts shows h
Contact: Gail Gallessich
University of California - Santa Barbara