X-Ray Light Used to Produce 3-D Model of Protein from Scratch

2013


X-Ray Light Used to Produce 3-D Model of Protein from Scratch

26 November 2013
 
Generating a complete 3-D pattern of a protein without being aware of its structure is now possible when an X-ray laser is deployed, a group of international scientists have proved. With the experiment, the team demonstrated X-ray lasers' potential for supporting studies of important biomolecules of unfamiliar structures that haven't been examined in detail so far due to the inability of conventional X-ray sources to analyze the tiny crystals they form.
 
The researchers, employed at the Department of Energy's (DOE) SLAC National Accelerator Laboratory, have created from scratch a precise model of lysozyme, an enzyme occurring naturally in egg whites, by using the Linac Coherent Light Source (LCLS) X-ray laser and complex computer analysis technology. The team, which was also joined by colleagues from Arizona State University and collaborators from SLAC, chose this particular enzyme for their experiment since science has been familiar with its structure for many years and its usage was expected to provide a good test of the method's viability.
 
For the purposes of the experiment, detailed in the journal Nature, the researchers soaked lysozyme crystals in a solution containing gadolinium, a metal that bound to the enzyme to generate a strong signal when the intense X-ray light was applied. The signal generated came from the gadolinium atoms that provided for the exact reconstruction of the lysozyme molecule.
 
The researchers now plan to work on the technique's adaptation to enable it to examine more complex proteins such as membrane proteins, which perform a variety of functions critical to the survival of organisms. Membrane proteins are also the target of over half of all new medicines being developed. This would be a major achievement since only a small percentage of the thousands of membrane proteins has been classified.