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Encyclopedia > Sedimentation equilibrium
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Sedimentation equilibrium is an analytical ultracentrifugation (AUC) method for measuring protein molecular masses in solution and for studying protein-protein interactions. It is particularly valuable for:


1) establishing whether the native state of a protein is a monomer, dimer, trimer, etc. 2) measuring the equilibrium constant (Kd) for association of proteins which reversibly self-associate to form oligomers 3) measuring the stoichiometry of complexes between two or more different proteins (e.g. a soluble receptor and its ligand or an antigen-antibody pair), or between a protein and a non-protein ligand 4) measuring the equilibrium constants for reversible protein-protein and protein-ligand interactions (approximate Kd range 1 nanomolar to 1 millimolar)


From http://www.ap-lab.com/sedimentation_equilibrium.htm


  Results from FactBites:
 
DS-820: Determination of Molecular Weights by Sedimentation Equilibrium (2812 words)
Sedimentation equilibrium provides a powerful method for determination of the quaternary structure of associating macromolecules, as well as for study of the stoichiometry of heterogeneous binding reactions.
Sedimentation equilibrium is especially preferred over sedimentation and diffusion in studies of polydisperse solutes, or for solutions containing high concentrations of salts or denaturing agents.
Conventional sedimentation equilibrium experiments are defined as those experiments that utilize a fluid column length of 3 to 5 mm in the centrifuge cell, with rotor speeds sufficiently low so that solute concentration at the meniscus is not zero, and with the entire contents of the cell at sedimentation equilibrium.
Sedimentation Velocity (1487 words)
Sedimentation velocity is an analytical ultracentrifugation (AUC) method that measures the rate at which molecules move in response to centrifugal force generated in a centrifuge.
A major advantage of this method over sedimentation equilibrium is that experiments usually require only 3-5 hours, as opposed to the several days typical of sedimentation equilibrium.
The minimum width of the sedimentation boundary is related to the diffusion coefficient of the molecule; the presence of multiple species with similar sedimentation coefficients will cause the boundary to be broader than expected on the basis of diffusion alone.
  More results at FactBites »


 

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