CRYSTALLIZATION IN LOOPS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The availability of protein crystals is a prerequisite to the determination of the three dimensional structure of proteins from x-ray diffraction experiments. Protein crystals are usually grown in hanging or sitting drops and generally get transferred to a loop or micromount for cryo-freezing and data collection. The transfer of crystals from drops is a ?tricky? process that often affects the quality of crystals and sometimes results in the loss of the crystal. However, the method of removing a crystal from a drop has not been automated, so a number of alternatives have been suggested to circumvent this problem. We have developed a method to grow protein crystals in cryoloops or micromounts. Growing crystals directly in cryoloops or micromounts has several advantages: a) it facilitates the automation of crystal handling; b) in some cases, it improves the quality of the diffraction ability (as we have been able to demonstrate from data measured on BL9-1 and BL9-2); and c) higher levels of supersaturation can be obtained in very small solution volumes enabling the exploration of additional crystallization conditions. The method will also allow efficient dehydration of crystals grown by other methods.