| Autor: |
Grant H. Barlow, E.T. Adams, John M. Beckerdite, Charlotte A. Weirich |
| Rok vydání: |
1983 |
| Předmět: |
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| Zdroj: |
Biophysical Chemistry. 17:203-210 |
| ISSN: |
0301-4622 |
| DOI: |
10.1016/0301-4622(83)87005-7 |
| Popis: |
If sedimentation equilibrium and sedimentation velocity experiments are performed on a self-associating solute under the same solution conditions, it is possible to evaluate the sedimentation coefficients (si) of the self-associating species and the usual concentration dependence parameter (g or gs). We have tested some of these methods with simulated examples. A more critical test is to use real data. Sedimentation equilibrium experiments with beta-lactoglobulin A at 20 degrees C in 0.2 M glycine buffer (pH 2.46) indicated that a nonideal monomer-dimer association was present. Sedimentation velocity experiments were performed on beta-lactoglobulin A under the same conditions. Using data from both sets of experiments we were able to evaluate s1, s2, g and gs using two different models for swa, the apparent weight average sedimentation coefficient. The empirical model for swa developed by Weirich et al. [1] gave better variance than did the model for swa developed by Gilbert and his co-workers [2-5]. Using a simulated monomer-dimer association mimicking a system having higher sedimentation coefficients than beta-lactoglobulin A did, we were able to show that one could not obtain s2 from tangents to the plot of 1/swa vs. c in the high concentration region. The methods developed here for sedimentation coefficients can be applied to other experiments in which a weight average property (or its apparent value) of a self-associating solute is measured, provided the appropriate thermodynamic experiments are done under the same solution conditions. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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