New recommendations for using X-rays promise to speed investigations aimed at understanding the structure and function of biologically important proteins information critical to the development of new drugs. Scientists from two U.S. Department of Energy national laboratories, Argonne and Brookhaven, and the University of Washington, Seattle, evaluated options to remedy problems affecting data collection in their new study.
Scientists who use powerful X-ray beams to study protein crystals face a dilemma: the beams provide the best tool for understanding a protein's structure and biological function, but they often damage the crystal, which may require repeated experiments that add time and cost to the research.
"Although X-ray crystallography is the go-to technique for determining protein structure and function, it is not without problems," said Andrzej Joachimiak at Argonne. The use of powerful X-ray beams causes radiation damage resulting in loss of data and the weak diffraction of crystals. In the end, this leads to an incomplete picture of the structure, and of how molecules interact with each other and their environment.
"The problem occurs when a protein crystal absorbs energy from incoming X-rays, which emits electrons that destroy or alter parts of the sample," Joachimiak said.
The research team examined three different X-ray-based methods for solving protein structures and recommended one called "submicrometer line focusing" as the most promising for easing the dilemma. As its name suggests, the beam strikes the protein crystal with an area smaller than a micrometer, or smaller than one thousandth of a millimeter. The tiny impact area minimizes damage. Also like its name, the beam is focused as a vertical line, delivering a more concentrated dose of X-rays per area.
The researchers also suggested using a new lens they designed that breaks the powerful beam into many mini-beams, spaced far enough apart that t
|Contact: Jared Sagoff|
DOE/Argonne National Laboratory