European Biophysics Journal

, Volume 47, Issue 3, pp 291–295 | Cite as

Allowance for radial dilution in evaluating the concentration dependence of sedimentation coefficients for globular proteins

  • Trushar R. PatelEmail author
  • Donald J. Winzor
  • David J. ScottEmail author
Original Article


The accuracy with which the concentration dependence of the sedimentation coefficient, s = s 0(1 − kc), can be quantified for globular proteins by commonly used procedures has been examined by subjecting simulated sedimentation velocity distributions for ovalbumin to c(s)‒s analysis. Because this procedure, as well as its g(s)‒s counterpart, is based on assumed constancy of s over the time course of sedimentation coefficient measurement in a given experiment, the best definition of the concentration coefficient k is obtained by associating the measured s with the mean of plateau concentrations for the initial and final distributions used for its determination. The return of a slightly underestimated k (by about 3%) is traced to minor mislocation of the air‒liquid meniscus position as the result of assuming time independence of s in a given experiment. Although more accurate quantification should result from later SEDFIT and SEDANAL programs incorporating the simultaneous evaluation of s 0 and k, the procedures based on assumed constancy of s suffice for determining the limiting sedimentation coefficient s 0—the objective of most sc dependence studies.


Concentration dependence Sedimentation coefficient Sedimentation velocity Ultracentrifugation 



Support of this investigation by the award of an NSERC Discovery Grant (RGPIN-2017-04003) to TRP is gratefully acknowledged. DJS is a Senior Molecular Biology and Neutron Fellow supported by the Science and Technology Facilities Council (UK).


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Copyright information

© European Biophysical Societies' Association 2017

Authors and Affiliations

  1. 1.Department of Chemistry and Biochemistry, Alberta RNA Research and Training InstituteUniversity of LethbridgeLethbridgeCanada
  2. 2.Discovery Lab, Medical Sciences BuildingUniversity of AlbertaEdmontonCanada
  3. 3.Department of Microbiology, Immunology and Infectious Diseases, Cumming School of MedicineUniversity of CalgaryCalgaryCanada
  4. 4.School of Chemistry and Molecular BiosciencesUniversity of QueenslandBrisbaneAustralia
  5. 5.National Center for Macromolecular Hydrodynamics, School of BiosciencesUniversity of NottinghamLoughboroughUK
  6. 6.ISIS Spallation Neutron and Muon SourceRutherford Appleton LaboratoryOxfordshireUK
  7. 7.Research Complex at HarwellRutherford Appleton LaboratoryOxfordshireUK

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