5-Prime | X-Ray-ted: A Crystal-Clear Lexicon

Courtesy of Steve Ealick

Crystal structures may clarify molecular organization, but the papers describing them are often so chock-full of jargon that they're largely unintelligible to those outside the crystallography field. Here are five prime definitions to get started.

Phase Problem: Crystallographers blast their crystals with X-rays and record the patterns of diffracted radiation. The intensities of diffracted X-rays give information about every molecule in the crystal, but tell little about the positions of the atoms relative to one another. That information comes from the diffracted X-rays' phase, which cannot be read from the diffraction pattern. To determine phase, crystallographers introduce reference points by soaking or engineering heavy metals into the crystal. Computers solve the phase problem by working from multiple data sets on these metal markers at known positions and the known amino acid sequence. This is the basis for techniques such...

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