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Search our Tips from A to Z for more information. Still having trouble finding what you want? Contact Hampton Research technical support.
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| L is for Light Scattering |
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| Dynamic light scattering, also known as DLS, also known as photon correlation spectroscopy, also known as quasi-elastic light scattering can be utilized to screen crystallization candidates for monodispersity.
DLS measures the translational diffusion coefficient of a macromolecular undergoing Brownian motion in a solution. What? In essence, DLS measures the intensity of light scattered by molecules in solution. In turn, this measurement can tell you the size distribution of the protein molecules in solution.
Crystal growers should use DLS to differentiate monodisperse solution from polydisperse solutions. Homogeneous, non-aggregated monodisperse proteins have a high probability of producing crystals. Proteins with non-specific aggregates and heterogeneous samples are less likely to crystallize. DLS allows one to screen protein samples quickly, with small volumes of sample, at different temperatures. The procedure is non-invasive so the protein can be recovered. If DLS is not an option one can obtain similar results using native polyacrylamide gel electrophoresis or size exclusion chromatography. But DLS is faster and more sensitive.
For a great story on DLS as well as practical information on methods for DLS read Terese Bergor's chapter on Dynamic Light Scattering in Protein Crystallization - Techniques, Strategies, and Tips - A Laboratory Manual.
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| L is for Lipidic Cubic Phases |
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| Membrane proteins can be crystallized in a lipid phase where the crystallization detergent diffuses into the lipid phase and crystal growth proceeds through lateral diffusion of the protein molecules.
References:
Lipidic cubic phases: a novel concept for the crystallization of membrane proteins. Proc Natl Acad Sci 1996, 93: 14532-14535
Related Reference:
X-ray crystallography of membrane proteins: Concepts and applications of lipidic mesophases to three-dimensional membrane protein crystallization G PROTEIN-COUPLED RECEPTORS. 2000. p.365-388 |
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| L is for Lyophilization |
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| Avoid lyophilization of your protein for storage and concentration if you plan to use the protein for crystallization experiments. Lyophilization is a not so gentle procedure and can prevent crystallization. Yes, we know that lyophilized lysozyme will crystallize quite readily as well as other "Sigma proteins" but we have seen, as well as others, many a protein that will not crystallize following lyophilization. And we have yet to see a protein that would only crystallized after lyophilization. So don't go there.
If you have a lyophilized protein there is hope. First of all, one should solubilize the protein in water or a stabilization buffer and dialyze the protein exhaustively against water or the stabilization buffer. Dialysis is an important step which will help to remove residual, non-volatile buffers and reagents as well as low molecular contaminants. |
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| L is for Lyotrope |
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| See Kosmotrope. |
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