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Repartitioning of NaCl and Protein Impurities in Lysozyme CrystallizationNonuniform precipitant and impurity incorporation in protein crystals can cause lattice strain and, thus, possibly decrease the X-ray diffraction resolution. To address this issue, a series of crystallization experiments were carried out, in which initial supersaturation, NaCl concentration, protein purity level and crystallized fraction were varied. Lysozyme and protein impurities, as well as sodium and chloride were independently determined in the initial solution, supernatant and crystals. The segregation coefficients for Na(+) and Cl(-) were found to be independent of supersaturation and NaCl concentration, and decreased with crystallized fraction/crystal size. Numerical evaluation of the extensive body of data, based on a nucleation-growth- repartitioning model, suggests a core of approx. 40 microns in which salt is incorporated in much greater concentrations than during later growth. Small crystals containing higher amounts of incorporated NaCl also had higher protein impurity contents. This suggests that the excess salt is associated with the protein impurities in the core. X-ray topography revealed strain fields in the center of the crystals comparable in size to the inferred core. The growth rates of crystals smaller than 30-40 pm in size were consistently 1.5-2 times lower than those of larger crystals, presumably due to higher chemical potentials in the core.
Document ID
19990049303
Acquisition Source
Marshall Space Flight Center
Document Type
Reprint (Version printed in journal)
Authors
Vekilov, Peter G.
(Alabama Univ. Huntsville, AL United States)
Monaco, Lisa A.
(Alabama Univ. Huntsville, AL United States)
Thomas, Bill R.
(Alabama Univ. Huntsville, AL United States)
Stojanoff, Vivian
(Brookhaven National Lab. Upton, NY United States)
Rosenberger, Franz
(Alabama Univ. Huntsville, AL United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1996
Publication Information
Publication: Acta Crystallographica Section D
Publisher: International Union of Crystallography
Volume: D52
ISSN: 0907-4449
Subject Category
Solid-State Physics
Funding Number(s)
CONTRACT_GRANT: NAG8-950
CONTRACT_GRANT: NAG8-1161
CONTRACT_GRANT: NSF DMB-91-04630
Distribution Limits
Public
Copyright
Other

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