Determination of Molecular Weights and Diffusion Coefficients in the Ultracentrifuge.

Ehrenberg, Anders; Lagerström, Gösta; Frydman, Mina; Sillén, Lars Gunnar

doi:10.3891/acta.chem.scand.11-1257

Cited by 288 publications

(41 citation statements)

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“…The diffusion coefficients determined from the slope of the i pc -ν 1/2 curves (2.63 ×10 −6 cm 2 /s for B-UNCD and 2.09 × 10 −6 cm 2 /s for B-MCD) are close to other reported values, 0.87 × 10 −6 cm 2 /s [1] and 1.1 × 10 −6 cm 2 /s [70,71]. There was some enhancement of the oxygen reduction current in naturally-aerated electrolyte solution after potential cycling in the presence of the redox protein.…”

Section: Discussionsupporting

confidence: 86%

Effects of Film Morphology and Surface Chemistry on the Direct Electrochemistry of Cytochrome c at Boron-Doped Diamond Electrodes

Dai

Proshlyakov

Swain

2016

Electrochimica Acta

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The effects of film morphology and surface termination on the direct electron transfer of horse heart cytochrome c on boron-doped ultrananocrystalline (B-UNCD) and microcrystalline (B-MCD) diamond thin-film electrodes were investigated. Quasi-reversible, diffusion-controlled cyclic voltammetric responses were observed on oxygen-terminated (atomic O/C ~0.015), but not hydrogen-terminated (atomic O/C ~0.02) diamond thin films. The effect of the surface termination was the same for both the nanostructured B-UNCD film with sp2-bonded carbon atoms in the grain boundaries and the well faceted B-MCD film with micron-sized grains and largely devoid of sp2 carbon. Stable cyclic voltammetric i-E curves were recorded with cycling for both oxygen-terminated films indicating the absence of protein denaturation and electrode fouling. The peak currents increased linearly with the square root of the scan rate and the protein concentration; both indicative of a reaction rate limited by semi-infinite linear diffusion of the protein. Similar heterogeneous electron-transfer rate constants were observed for oxygen-terminated B-UNCD (3.48 (± 1.25) × 10−3 cm/s) and B-MCD films (2.38 (± 0.72) × 10−3 cm/s). The results clearly reveal that the oxygen-terminated surface is more active for electron-transfer with this soluble redox protein than is the hydrogen-terminated surface. The film morphology does not influence the diffusion-controlled response of the redox protein.

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Section: Discussionsupporting

confidence: 86%

Effects of Film Morphology and Surface Chemistry on the Direct Electrochemistry of Cytochrome c at Boron-Doped Diamond Electrodes

Dai

Proshlyakov

Swain

2016

Electrochimica Acta

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“…The correction factors used can be found in the text. 5 Determined spectrophotometrically. 6 Determined by the Conway diffusion method.…”

Section: Resultsmentioning

confidence: 99%

Nature of the Conversion of Ficus carica Variety Kadota Ficin Component D to Component C. Some Physicochemical Properties of Components C and D

Kramer

Whitaker

1969

Plant Physiol.

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Component C can be formed from component D under the experimental conditions used during purification of Ficus carica variety Kadota latex. By use of the inhibitor, sodium p-chloromercuribenzoate, the 2 components have been purified to chromatographic homogeneity. The 2 components have identical molecular weights and amino acid composition. The only difference found between the 2 components is the presence of 3 to 6 more amide groups in component D than in component C. There also appears to be a conformational difference between the 2 since component C is not as acidic, with respect to component D, as would be expected from the comparative amide contents. Conformational differences between the 2 are also indicated by the chromatographic behavior of the 2 in the presence and absence of sodium-p-chloromercuribenzoate.

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“…The operational extinction coefficient of cytochrome c at the higher wavelength (106 000 M -1 cm -1 ) was based on that at 280 nm and the ratio of absorbances at the two wavelengths for a solution of cytochrome c. Partial specific volumes of the two proteins were taken as 0.748 mL/g for ovalbumin (15) and 0.728 mL/g for cytochrome c (16). The density of the buffer (diffusate) was determined as 0.9999 g/mL at 20°C by standard procedures in an Anton Paar density meter.…”

Section: Methodsmentioning

confidence: 99%

Direct Analysis of Sedimentation Equilibrium Distributions Reflecting Complex Formation between Dissimilar Reactants

1998

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Procedures are developed for the characterization of thermodynamically ideal complex formation between dissimilar macromolecular reactants by direct analysis of sedimentation equilibrium distributions. Studies of an electrostatic interaction between ovalbumin and cytochrome c are used to illustrate the application of analyses pertaining to (i) the situation in which separate sedimentation equilibrium distributions for the two macromolecular constituents are available, (ii) that in which the experimental record reflects the distribution of only one constituent, and (iii) the situation in which a composite distribution for both constituents is the sole experimental record. An association constant of 63 000 (+/- 2000) M-1 is obtained for the 1:1 interaction between ovalbumin and cytochrome c under the conditions examined (pH 6.3, I 0.03). Because of their inherent simplicity, these direct analytical procedures offer potential for accommodating the effects of thermodynamic nonideality in dissimilar reactant systems.

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Determination of Molecular Weights and Diffusion Coefficients in the Ultracentrifuge.

Cited by 288 publications

References 0 publications

Effects of Film Morphology and Surface Chemistry on the Direct Electrochemistry of Cytochrome c at Boron-Doped Diamond Electrodes

Effects of Film Morphology and Surface Chemistry on the Direct Electrochemistry of Cytochrome c at Boron-Doped Diamond Electrodes

Nature of the Conversion of Ficus carica Variety Kadota Ficin Component D to Component C. Some Physicochemical Properties of Components C and D

Direct Analysis of Sedimentation Equilibrium Distributions Reflecting Complex Formation between Dissimilar Reactants

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