The researchers accomplished their work by combining two popular synchrotron techniques x-ray diffraction and optical absorption spectroscopy into one setup. By shining beams of powerful x-rays and visible light on the same region of the crystallized flavoprotein, two different but complementary sets of information are received. This allows the scientists to correlate the electronic structure of the enzyme which gives details about chemical activities with its three-dimensional atomic structure.
"The ability to collect multiple types of data from the same sample at the same time is a unique opportunity," Orville said. "It takes less time and it means you never have to move the sample and risk altering it in any way. It also removes many potential ambiguities that either technique alone cannot resolve."
To stabilize the flavoprotein intermediate, the researchers kept it at an extremely low temperature about -280 degrees Fahrenheit. When exposed to the x-rays, the cold flavoprotein rapidly accepts electrons liberated in the sample by the x-ray beam. This starts the enzyme reaction, which progresses a bit further and then becomes trapped in its reactive intermediate state. Using the combined data, the group identified two possible intermediate structures. Further experiments will help determine which is the true intermediate.
Orville is installing additional complementary techniques at the NSLS. Planning also is underway for several beamlines with multiple complementary techniques at the National Synchrotron Light Source II, a new, proposed Brookhaven facility that will produce x-rays up to 10,000 times brighter than those at the NSLS. The hope is to provide a means for researchers to simultaneously obtain three or four different
|Contact: Kendra Snyder|
DOE/Brookhaven National Laboratory