Lasers Are Used to Align Molecules

U.S. scientists say difficulties involved with crystallizing molecules for synchrotron X-ray diffraction can be resolved by using lasers.

Strong laser fields can be used to control the behavior of atoms and molecules, said Argonne National Laboratory scientist Linda Young. Using X-rays, we can investigate their properties in a totally new way.

Crystallization allows scientists to create a periodic structure that will strongly diffract in specific directions when bombarded with X-rays. From the resulting diffraction pattern, a real-space image can be reconstructed.

However, without crystallization, it is impossible to create a composite diffraction image, Argonne Physicist Robin Santra said.

Understanding the structure of the approximately 1 million human proteins that cannot be crystallized is perhaps the most important challenge facing structural biology, Young said. A method for structure determination at atomic resolution without the need to crystallize would be revolutionary.

Young and her team have successfully aligned molecules using a laser, probed the aligned ensemble with X-rays and shown theoretically that the technique could be used for X-ray imaging. However, they said an upgrade to the lab’s Advanced Photon Source facility is needed before X-ray diffraction can be done experimentally.

The study appears in the journal Applied Physics Letters.