"We haven't really been able to study dynamics, to see if a chemical reaction like protein folding varies inside of a living cell," he said. "With temperature jumps and pressure jumps, you can do those experiments very quickly, but you don't get any imagery that lets you see if proteins fold faster in one region and slower in another," Gruebele said.
On the other hand, fluorescence microscopy allows researchers to see inside of cells, but it precludes them from studying cell dynamics and kinetics.
"With fluorescence microscopy, we're able to take images of cells and see inside them, but we can't observe how anything rapidly changes or adapts with time, so you can't look at any but the slowest dynamics. This experiment puts those two aspects together," he said.
Since biomolecular dynamics are predominantly studied in vitro, with the results extrapolated to explain how the same processes would function in a living cell, Gruebele says the new technique has yielded some interesting data that could change standard thinking in the field.
"If you perform experiments only in an artificial environment such as a test tube and not in a living cell, you only get one answer," Gruebele said. "It's a reproducible environment; therefore, it always gives you the same answer. If you do it in a cell, we find we get very different answers in different parts of the cell."
According to Gruebele, the proteins studied in vivo using the new technique were more stable, their thermal denaturation was more gradual and their folding kinetics were slower than the same proteins studied in vitro.
Gruebele said that in living cells, "You really expect a lot of heterogeneity, that there would be a lot of differences among different areas of the cell, that th
|Contact: Phil Ciciora|
University of Illinois at Urbana-Champaign