A Modification of Fujita's Method for the Calculation of Diffusion Coefficients From Boundary Spreading in the Ultracentrifuge

Abstract

NotesVol. 64 fusion. Put in. another manner, as far as diffusion is concerned the diaphragm does effectively behave as if it were made up of a series of parallel capillaries.

β‐Methylcrotonyl‐CoA‐Carboxylase

“…Den Diffusionskoeffizienten erhielt man nach dem Verfahren von Fujita und van Holde [23,24] ebenfalls aus Experimenten in der analytischen Ultrazentrifuge. 4 Versuche (Fig.…”

“…7 Versuche bei verschiedenen Proteinkonzentrationen (Fig. 6) ergaben bei graphischer Extrapolation auf unendliche Verdiinnung den Wert s:~,, = 20,7 S. Den Diffusionskoeffizienten erhielt man nach dem Verfahren von Fujita und van Holde [23,24] ebenfalls aus Experimenten in der analytischen Ultrazentrifuge. 4 Versuche (Fig.…”

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

“…Fortunately, an erroneous magnitude for k s does not affect the value of s o , the parameter most commonly being sought because of its relevance to the prediction of protein shape from hydrodynamic parameters (Garcia de la Torre et al 2000; Garcia de la Torre and Harding, 2013), although k s , if measured correctly, is itself useful in the delineation of molecular shape. In the event that the extent of boundary spreading is being used to evaluate the translational diffusion coefficient D the magnitude of k s also becomes important because of its use to make quantitative allowance for the effects of boundary sharpening arising from the linear negative s-c dependence exhibited by globular proteins (Fujita 1956(Fujita , 1959Baldwin 1957;Van Holde 1960;Scott et al 2015;Winzor and Scott 2018;Chaturvedi et al 2018). In that regard, the recommendation that use of the commonly used SEDFIT program for determining protein molar mass from sedimentation velocity distributions be confined to the analysis of experiments with low loading concentrations (Schuck 2005) reflected the omission of any allowance for this boundary sharpening effect at that stagea point now emphasized in the recent study dealing with the consequences of hydrodynamic nonideality (Chaturvedi et al 2018).…”

Allowance for boundary sharpening in the determination of diffusion coefficients by sedimentation velocity: a historical perspective

“…A major breakthrough in the analysis of boundary spreading in sedimentation velocity experiments was the report by Fujita (1956Fujita ( , 1962 of an approximate analytical solution to the Lamm equation for solutes exhibiting linear concentration dependence of s and concentration independence of D. Other approximate solutions (Weiss 1964;Weiss and Yphantis 1965;Billick and Weiss 1966) were precursors to the application of numerical simulation for solving the Lamm equation (Dishon et al 1967) that finally generated concentration gradient distributions demonstrating the adequacy of the Fujita approximate analytical solution. Only limited advantage was taken of this breakthrough (Baldwin 1957;Van Holde 1960;Creeth and Winzor 1962;Inkerman et al 1975) before the virtual demise of analytical ultracentrifugation soon thereafter-a technique that was only revitalized by the appearance of a new-generation instrument in the final decade of the twentieth century. A second factor was the movement away from the less sensitive schlieren optical system to UV absorbance optics-a change that allowed experimental data to be obtained at much lower protein concentrations (a lower limit of about 10 μg/ml), where the effects of hydrodynamic nonideality leading to boundary sharpening are negligible.…”

“…On grounds of historical significance it seems timely to review the literature on the much earlier practice (Baldwin 1957;Van Holde 1960) of employing the approximate analytical solution (Fujita 1956(Fujita , 1962 of the Lamm equation to determine the diffusion coefficient from sedimentation velocity distributions that reflect the boundary sharpening resulting from linear s−c dependence; and also to take advantage of a current numerical integration procedure (Schuck 1998(Schuck , 2000 for solving the Lamm equation to provide simulated sedimentation velocity distributions that allow more critical assessment of the consequences of the enforced simplification on which the approximate solution is based. Although the effort and understanding required to employ those analytical procedures is likely to preclude any future applications, their review at this time serves to emphasize the advanced level of boundary spreading analysis that had been attained over 60 years ago.…”