Sedimentation velocity of polymer solutions—I. Concentration dependence of the sedimentation coefficient

1968 ◽  
Vol 4 (6) ◽  
pp. 639-649 ◽  
Author(s):  
W.J. Closs ◽  
B.R. Jennings ◽  
H.G. Jerrard
Keyword(s):  
Concentration Dependence ◽  
Polymer Solutions ◽  
Sedimentation Coefficient ◽  
Sedimentation Velocity

scholarly journals Quantifying the concentration dependence of sedimentation coefficients for globular macromolecules: a continuing age-old problem

2021 ◽  
Author(s):  
Donald J. Winzor ◽  
Vlad Dinu ◽  
David J. Scott ◽  
Stephen E. Harding
Keyword(s):  
Concentration Dependence ◽  
Diffusion Coefficients ◽  
Sedimentation Coefficient ◽  
Sedimentation Velocity ◽  
Translational Diffusion ◽  
Optical Systems ◽  
Coefficient Measurement ◽  
Retrospective Investigation ◽  
Linear Concentration

AbstractThis retrospective investigation has established that the early theoretical attempts to directly incorporate the consequences of radial dilution into expressions for variation of the sedimentation coefficient as a function of the loading concentration in sedimentation velocity experiments require concentration distributions exhibiting far greater precision than that achieved by the optical systems of past and current analytical ultracentrifuges. In terms of current methods of sedimentation coefficient measurement, until such improvement is made, the simplest procedure for quantifying linear s-c dependence (or linear concentration dependence of 1/s) for dilute systems therefore entails consideration of the sedimentation coefficient obtained by standard c(s), g*(s) or G(s) analysis) as an average parameter ($$ \overline{s} $$ s ¯ ) that pertains to the corresponding mean plateau concentration (following radial dilution) ($$ \overline{c} $$ c ¯ ) over the range of sedimentation velocity distributions used for the determination of $$ \overline{s} $$ s ¯ . The relation of this with current descriptions of the concentration dependence of the sedimentation and translational diffusion coefficients is considered, together with a suggestion for the necessary improvement in the optical system.

scholarly journals Nitrogenase of Klebsiella pneumoniae. Interaction of the component proteins studied by ultracentrifugation

1973 ◽  
Vol 135 (3) ◽  
pp. 531-535 ◽  
Author(s):  
Robert R. Eady
Keyword(s):  
Klebsiella Pneumoniae ◽  
Sedimentation Coefficient ◽  
Sedimentation Velocity ◽  
Single Peak ◽  
Molar Ratio ◽  
Titration Curves ◽  
Additional Peak

Sedimentation-velocity analyses of mixtures of the component proteins of nitrogenase of Klebsiella pneumoniae at a 1:1 molar ratio, showed a single peak of sedimentation coefficient (12.4S) considerably greater than that obtained for the larger (Fe+Mo-containing) protein centrifuged alone (10.4S). When the ratio exceeded 1:1 (the smaller Fe-containing protein in excess) an additional peak corresponding in sedimentation coefficient (about 4.5S) to free Fe-containing protein appeared. When proteins, which had been inactivated by exposure to air were used, no interaction occurred. Na2S2O4 at 2mm both reversed and prevented interaction between the two proteins; sedimentation coefficients corresponded to those of the proteins when centrifuged alone. These results demonstrate the formation of a complex between the nitrogenase proteins, and, together with data of activity titration curves, are consistent with the formulation of the nitrogenase complex of K. pneumoniae as (Fe-containing protein)–(Fe+Mo-containing protein).

Sign in / Sign up

Export Citation Format

Share Document