Evaluation of diffusion coefficients by means of an approximate steady-state condition in sedimentation velocity distributions

Scott, David J.; Harding, Stephen E.; Winzor, Donald J.

Abstract

This investigation examined the feasibility of manipulating the rotor speed in sedimentation velocity experiments to spontaneously generate an approximate steady-state condition where the extent of diffusional spreading is matched exactly by the boundary sharpening arising from negative s–c dependence. Simulated sedimentation velocity distributions based on the sedimentation characteristics for a purified mucin preparation were used to illustrate a simple procedure for determining the diffusion coefficient from such steady-state distributions in situations where the concentration dependence of the sedimentation coefficient, s = s0/(1 + Kc), was quantified in terms of the limiting sedimentation coefficient as c → 0 (s0) and the concentration coefficient (K). Those simulations established that spontaneous generation of the approximate steady state could well be a feature of sedimentation velocity distributions for many unstructured polymer systems because the requirement that Kcoω2s0/D be between 46 and 183 cm−2 is not unduly restrictive. Although spontaneous generation of the approximate steady state is also a theoretical prediction for structured macromolecular solutes exhibiting linear concentration dependence of the sedimentation coefficient, s = s0(1 − kc), the required value of k is far too large for any practical advantage to be taken of this approach with globular proteins.

Citation

Scott, D. J., Harding, S. E., & Winzor, D. J. (2015). Evaluation of diffusion coefficients by means of an approximate steady-state condition in sedimentation velocity distributions. Analytical Biochemistry, 490, https://doi.org/10.1016/j.ab.2015.08.017

• Journal Article Type: Article
• Acceptance Date: Aug 13, 2015
• Online Publication Date: Aug 28, 2015
• Publication Date: Dec 1, 2015
• Deposit Date: May 10, 2017
• Journal: Analytical Biochemistry
• Print ISSN: 0003-2697
• Electronic ISSN: 1096-0309
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 490
• DOI: https://doi.org/10.1016/j.ab.2015.08.017
• Keywords: Diffusion coefficient; Sedimentation velocity; Ultracentrifugation
• Public URL: https://nottingham-repository.worktribe.com/output/765055
• Publisher URL: http://www.sciencedirect.com/science/article/pii/S0003269715003930