Current Crystallization Protocol
This drawing shows a somewhat facetious representation of the steps currently involved in crystallization. One guesses conditions for crystallizing a particular material, and then sets up crystallization experiments. Those so inclined are free to ask assistance from any source to aid the crystallization process. One then seeks crystals: If crystals of adequate quality have been obtained, one can go off and execute the x-ray diffraction experiment. If not, there is rarely much feedback information about the molecular basis of the failure. One may then seek assistance from other sources, or to guess new conditions, and to cycle either procedure until success is obtained. The point of this cartoon is that it is much harder to debug a crystallization experiment than any other experiment, because of the lack of feedback. Every aspect of the crystallization conditions must be suitable for obtaining crystals; if any one of them is wrong, crystals will not result. It is sort of like trying to crack a safe without the aid of a stethoscope: Every combination must be tried. With a stethoscope, each part of the combination can be worked out sequentially.
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