Shooting movies of molecules
Scientists at the U.S. Department of Energy's (DOE) Argonne National Laboratory have developed techniques for creating movies of biological and chemical molecules. It has been done before for crystalline structures of salt or metals, but organic molecules are more complex, and more difficult to catch. Until now, researchers had to rely on computer simulations to visualize molecular motions in solution. This is the first time that scientists can see the movements of biological molecules and compare them to their theoretical counterparts. But read more...
You can see on the left a frame extracted from a GIF animation showing how Argonne scientists have used high intensity X-rays to create 'movies' of biological and organic molecules. (Credit: Argonne National Laboratory) Here is a link to this DNA movie.
This research project has been led by David Tiede, Group Leader and Senior Chemist at the Photosynthesis Group, who also works for the Advanced Photon Source (APS), a national synchrotron X-ray research facility funded by the U.S. Department of Energy.
The team was not able to 'see' the motions of these molecules, which are constantly evolving. Instead, they've "measured images that are 'blurred' by these motions and have used them to create more accurate movies of molecular motions." As said Tiede, "The blurring that we see in our solution x-ray patterns are remarkably sensitive to the type of the molecular motion. For the first time, we are able to test the accuracy of the simulation and change it to fit data better. Without it, we had no way of knowing how accurate the models were."
And what's coming next? "Tiede hopes an improved accuracy in molecular modeling will give insights into the structure and behavior of the molecules. Collaborators at the National Institutes of Health have used this approach to help determine structures of important biological molecules. 'We hope to establish between 'good' and 'bad' molecular actors in important chemical processes like photosynthesis, solar energy and catalysts,' Tiede said. 'Once we see that, we can make these processes work better.'"
For more information about this research project, here are three articles to read.
- "Coordinative Self-Assembly and Solution-Phase X-ray Structural Characterization of Cavity-Tailored Porphyrin Boxes" (Journal of the American Chemical Society, Volume 130, Issue 3, Pages 836-838, January 23, 2008, link to abstract)
- "Photocatalytic probing of DNA sequence by using TiO2/dopamine-DNA triads" (Chemical Physics, Volume 339, Issues 1-3, Pages 154-163, October 15, 2007, link to abstract)
- "Solution-Phase Structural Characterization of Supramolecular Assemblies by Molecular Diffraction" (Journal of the American Chemical Society, Volume 129, Issue 6, Pages 1578-1585, February 14, 2007, link to abstract)
Sources: Argonne National Laboratory, April 15, 2008; and various websites
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