Evaluation of diffusion coefficients by means of an approximate steadystate condition in sedimentation velocity distributionsTools Scott, David J. and Harding, Stephen E. and Winzor, Donald J. (2015) Evaluation of diffusion coefficients by means of an approximate steadystate condition in sedimentation velocity distributions. Analytical Biochemistry, 490 . pp. 2025. ISSN 10960309
AbstractThis investigation examined the feasibility of manipulating the rotor speed in sedimentation velocity experiments to spontaneously generate an approximate steadystate 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 steadystate 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.
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