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The Growth of Protein Crystals Using McDUCKMost of the current microgravity crystal growth hardware is optimized to produce crystals within the limited time available on orbit. This often results in the actual nucleation and growth process being rushed or the system not coming to equilibrium within the limited time available. Longer duration hardware exists, but one cannot readily pick out crystals grown early versus those which nucleated and grew more slowly. We have devised a long duration apparatus, the Multi-chamber Dialysis Unit for Crystallization Kinetics, or McDUCK. This apparatus-is a series of protein chambers, stacked upon a precipitant reservoir chamber. All chambers are separated by a dialysis membrane, which serves to pass small molecules while retaining the protein. The volume of the Precipitant chamber is equal to the sum of the volumes of the protein chamber. In operation, the appropriate chambers are filled with precipitant solution or protein solution, and the McDUCK is placed standing upright, with the precipitant chamber on the bottom. The precipitant diffuses upwards over time, with the time to reach equilibration a function of the diffusivity of the precipitant and the overall length of the diffusion pathway. Typical equilibration times are approximately 2-4 months, and one can readily separate rapid from slow nucleation and growth crystals. An advantage on Earth is that the vertical precipitant concentration gradient dominates that of the solute, thus dampening out solute density gradient driven convective flows. However, large Earth-grown crystals have so far tended to be more two dimensional. Preliminary X-ray diffraction analysis of lysozyme crystals grown in McDUCK have indicated that the best, and largest, come from the middle chambers, suggesting that there is an optimal growth rate. Further, the improvements in diffraction resolution have been better signal to noise ratios in the low resolution data, not an increase in resolution overall. Due to the persistently large crystals grown we are currently proposing McDUCK for the growth of macromolecule crystals for use in neutron diffraction studies.
Document ID
19980236896
Document Type
Reprint (Version printed in journal)
Authors
Ewing, Felicia (Universities Space Research Association Huntsville, AL United States)
Wilson, Lori (State Univ. of East Tennessee Johnson City, TN United States)
Nadarajah, Arunan (Toledo Univ. OH United States)
Pusey, Marc (NASA Marshall Space Flight Center Huntsville, AL United States)
Date Acquired
August 18, 2013
Publication Date
January 1, 1998
Subject Category
Solid-State Physics
Meeting Information
Crystallization of Biological Maromolecules(Granada)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.