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Issue 23, 2014
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Concentration dependence of translational diffusion coefficients for globular proteins

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Abstract

This investigation examines published results of traditional diffusion experiments on ovalbumin and bovine serum albumin to determine the extent to which assumed concentration independence of the translational diffusion coefficient is a reasonable approximation in the analysis of boundary spreading in sedimentation velocity experiments on proteins. Although significant positive concentration dependence of the diffusion coefficient (D) for both proteins is predicted by current theories, none has been detected in these experimental diffusion studies performed under the constraints of constant temperature and solvent chemical potential (those also pertinent to sedimentation velocity). Instead, the results are better described by the relatively minor concentration dependence predicted by considering solution viscosity to be an additional source of Dc dependence. Inasmuch as the predicted variation in D for solutions with concentrations below 10 mg mL−1 is within the uncertainty of experimental estimates, these findings support use of the approximate solution of the Lamm equation developed by Fujita for the quantitative analysis of boundary spreading in sedimentation velocity experiments on proteins.

Graphical abstract: Concentration dependence of translational diffusion coefficients for globular proteins

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Publication details

The article was received on 11 Jun 2014, accepted on 22 Sep 2014 and first published on 22 Sep 2014


Article type: Paper
DOI: 10.1039/C4AN01060D
Author version available: Download Author version (PDF)
Citation: Analyst, 2014,139, 6242-6248
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    Concentration dependence of translational diffusion coefficients for globular proteins

    D. J. Scott, S. E. Harding and D. J. Winzor, Analyst, 2014, 139, 6242
    DOI: 10.1039/C4AN01060D

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