Correcting for cell tilt caused by differential expansion of rotors in the analytical ultracentrifuge

Gropper, L.

doi:10.1016/0003-2697(63)90107-6

Cited by 4 publications

(2 citation statements)

References 2 publications

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“…The shape of the optical artifact itself can be expected to be highly sensitive to optical alignment, sample and solvent properties, sample concentration, rotor speed, centerpiece material, etc. as was studied in detail previously by several investigators (Trautman 1958 ; Erlander and Babcock 1961 ; Gropper 1963 ). Gropper has pointed out that with the focus of the optics being at the 2/3 plane of the solution column, the meniscus position will not appear at the correct image location (Gropper 1964 ).…”

Section: Discussionmentioning

confidence: 69%

On the analysis of sedimentation velocity in the study of protein complexes

2009

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Sedimentation velocity analytical ultracentrifugation has experienced a significant transformation, precipitated by the possibility of efficiently fitting Lamm equation solutions to the experimental data. The precision of this approach depends on the ability to account for the imperfections of the experiment, both regarding the sample and the instrument. In the present work, we explore in more detail the relationship between the sedimentation process, its detection, and the model used in the mathematical data analysis. We focus on configurations that produce steep and fast-moving sedimentation boundaries, such as frequently encountered when studying large multi-protein complexes. First, as a computational tool facilitating the analysis of heterogeneous samples, we introduce the strategy of partial boundary modeling. It can simplify the modeling by restricting the direct boundary analysis to species with sedimentation coefficients in a predefined range. Next, we examine factors related to the experimental detection, including the magnitude of optical aberrations generated by out-of-focus solution columns at high protein concentrations, the relationship between the experimentally recorded signature of the meniscus and the meniscus parameter in the data analysis, and the consequences of the limited radial and temporal resolution of the absorbance optical scanning system. Surprisingly, we find that large errors can be caused by the finite scanning speed of the commercial absorbance optics, exceeding the statistical errors in the measured sedimentation coefficients by more than an order of magnitude. We describe how these effects can be computationally accounted for in SEDFIT and SEDPHAT.

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Section: Discussionmentioning

confidence: 69%

On the analysis of sedimentation velocity in the study of protein complexes

2009

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“…Regardless of the frames used, and allowing for some uncertainty about the equivalent UTS (up-to-speed) time, the calculated base-of-cell position can be displaced from the observed base-of-cell by as much as 0.2 ram in the direction of the knife edge. A part of this displacement may be attributed to cell tiIt (7), estimated to be the order of 0.1 ram. In addition, the presence of an inconspicuously small amount of sedimenting lipoprotein or protein can give rise to a false base-of-cell that moves out slightly from the true base-of-cell as a function of time.…”

Section: Thementioning

confidence: 98%

Serum lipoprotein distribution, flotation rates and protein analysis

Lindgren

Freeman

Ewing

et al. 1966

J Americ Oil Chem Soc

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Flotation rates of the major Sf 0-12 lowdensity lipoprotein component in human serum may be calculated from ultracentrifuge data utilizing two computer programs. One program calculates a classical moving boundary uncorrected flotation rate by a best fit straight line for the points (ln x~, ~2t~). The other program permits correction for concentration dependence and correction to standard reference conditions. Preliminary application of these methods indicates significantly greater flotation rates in normal human females than in males for the 35-49 year age group.The significance of interrelationships between the serum lipoprotein spectra, the serum lipids and the serum proteins is considered, resulting in the development of a revised method of measuring serum proteins by precision refractometry. The refractometric measurement is corrected in accordance with (any of various) lipid measurements in order to account for the contribution of lipoproteins to the total refractive increment. Such a technique, giving potentially a very accurate protein measurement, has application in screening studies involving abnormalities of both serum lipoprotein and serum protein metabolism.

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Optical alignment procedure for the analytical ultracentrifuge

Gropper¹

1964

Analytical Biochemistry

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Correcting for cell tilt caused by differential expansion of rotors in the analytical ultracentrifuge

Cited by 4 publications

References 2 publications

On the analysis of sedimentation velocity in the study of protein complexes

On the analysis of sedimentation velocity in the study of protein complexes

Serum lipoprotein distribution, flotation rates and protein analysis

Optical alignment procedure for the analytical ultracentrifuge

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