The Intrinsic Viscosities and Diffusion Constants of Flexible Macromolecules in Solution

1948 ◽  
Vol 16 (6) ◽  
pp. 565-573 ◽  
Author(s):  
John G. Kirkwood ◽  
Jacob Riseman
Keyword(s):  
Diffusion Constants ◽  
And Diffusion

ULTRACENTRIFUGE AND DIFFUSION STUDIES ON GLUTEN

1942 ◽  
Vol 20c (3) ◽  
pp. 130-159 ◽  
Author(s):  
A. G. McCalla ◽  
Nils Gralén
Keyword(s):  
Sodium Salicylate ◽  
Minimum Weight ◽  
Average Molecular Weight ◽  
Sedimentation Equilibrium ◽  
Velocity Sedimentation ◽  
Molecular Characteristics ◽  
Weight Average Molecular Weight ◽  
Diffusion Constants ◽  
Diffusion Studies ◽  
And Diffusion

The molecular characteristics of gluten in sodium salicylate solutions were studied by means of sedimentation velocity, sedimentation equilibrium, and diffusion measurements. The proportion of total gluten protein molecularly dispersed increased with increase in concentration of sodium salicylate up to 12%, but the dispersed portions had essentially the same sedimentation constant (2.5 ± 0.15) regardless of the concentration of the dispersing medium.The most soluble 25 per cent of the gluten was all molecularly dispersed, but was definitely inhomogeneous. The weight-average molecular weight of this fraction was 44,000, but there is reason to believe the minimum weight may be about 35,000. None of the other fractions was entirely molecularly dispersed, the proportion decreasing with decreasing solubility of the fractions. Aggregates of many sizes existed in all of these fractions, but only the most insoluble contained aggregates large enough to cause opacity. Sedimentation constants of the molecularly dispersed portions increased slightly with decreasing solubility, while diffusion constants decreased markedly. None of the fractions yielded normal curves (diffusion diagrams) but the more soluble the fraction, the more nearly normal the curve. The inhomogeneity responsible for the varying rates of diffusion was due partly to differences in proportion and properties of the molecularly dispersed gluten and partly to aggregates.All properties showed progressive changes both within and between the arbitrarily produced fractions. These results, therefore, support the hypothesis that gluten is a protein system showing progressive and regular changes in properties with change in solubility.

Watching small molecules move: Interrogating ionic channels using neutral solutes

1995 ◽  
Vol 15 (6) ◽  
pp. 503-514 ◽  
Author(s):  
V. A. Parsegian ◽  
S. M. Bezrukov ◽  
I. Vodyanoy
Keyword(s):  
Osmotic Stress ◽  
Ionic Channels ◽  
Ionic Channel ◽  
Water Molecules ◽  
Chemical Potentials ◽  
Diffusion Constants ◽  
Functional States ◽  
Channel Space ◽  
And Diffusion ◽  
Osmotic Activity

Whether they are small enough to wriggle through the current-carrying part of an ionic channel or big enough to be kept outside and thus able to exert an osmotic stress on the channel space, polymers interact with channels in several instructive ways. The osmotic stress of excluded polymers allows one to measure the number of water molecules that come out of the channel in transitions between various “open” to “closed” states. The loss of osmotic activity, due to the partial or completely unrestricted admission of small polymers becomes a measure of the transfer probabilities of polymers from solution to small cavities; it provides an opportunity to study polymer conformation in a perfectly sieved preparation. Current fluctuations due to the partial blockage by a transient polymer are converted into estimates of times of passage and diffusion constants of polymers in channels. These estimates show how a channel whose functional states last for milliseconds is able to average over the interactions with polymers, interactions that last only microseconds. One sees clearly that in this averaging, the macromolecular channel is large enough to react like a macroscopic object to the chemical potentials of the species that modulate its activity.

scholarly journals Ultrafast Laplace NMR to study metal-ligand interactions in reversible polarisation transfer from parahydrogen

2021 ◽  
Author(s):  
Ben. J. Tickner ◽  
Vladimir V. Zhivonitko ◽  
Ville-Veikko Telkki
Keyword(s):  
Molecular Structure ◽  
Relaxation Times ◽  
The Self ◽  
Self Diffusion ◽  
Structure And Dynamics ◽  
Relaxation Parameters ◽  
Diffusion Constants ◽  
Ligand Interactions ◽  
And Diffusion ◽  
Metal Ligand

Laplace Nuclear Magnetic Resonance (NMR) can determine relaxation parameters and diffusion constants, giving valuable information about molecular structure and dynamics. Information about relaxation times (T1 and T2) and the self-diffusion...

scholarly journals ANTIGEN-ANTIBODY REACTIONS BETWEEN LAYERS ADSORBED ON BUILT UP STEARATE FILMS

1939 ◽  
Vol 69 (6) ◽  
pp. 755-765 ◽  
Author(s):  
Eliot F. Porter ◽  
Alwin M. Pappenheimer
Keyword(s):  
Specific Antibody ◽  
Diphtheria Toxin ◽  
Alternate Treatment ◽  
Molecular Weights ◽  
Adsorbed Protein ◽  
Diffusion Constants ◽  
Barium Stearate ◽  
Immunological Reactions ◽  
Antigen Antibody ◽  
And Diffusion

By adsorbing antigens and antibodies on barium stearate multilayers immunological reactions at surfaces have been studied. Pneumococcus polysaccharide specific antibody systems using purified antibodies from both horse and rabbit sera were investigated. The polysaccharides failed to show visible adsorption, but by alternate treatment with antibody and polysaccharide several layers of antibody could be specifically deposited. With the diphtheria toxin-antitoxin system antitoxin was found to adsorb to layers of toxin but not conversely. The reaction, however, was not specific. Molecular weights calculated from the thickness of adsorbed protein layers, using dissymmetry factors, roughly correspond to molecular weights calculated from sedimentation and diffusion constants.

Das Molekulargewicht der Peptideinheit im Protein des Tabakmosaikvirus

1959 ◽  
Vol 14 (1) ◽  
pp. 24-28 ◽  
Author(s):  
F. Alfred Anderer
Keyword(s):  
Molecular Weight ◽  
Tobacco Mosaic Virus ◽  
Mosaic Virus ◽  
Alkaline Solution ◽  
Diffusion Constants ◽  
And Diffusion

The protein of tobacco mosaic virus was extracted by phenol. After precipitation with methanol the sedimentation and diffusion constants were measured in alkaline solution. At pH 13,0 S20=2.0 and D20=9.6 was found. From these data a molecular weight of 18 800 ± 10% can be calculated, which corresponds to the size of the peptide subunit found by the endgroup determination.

scholarly journals THE MOLECULAR WEIGHT AND ISOELECTRIC POINT OF THYROGLOBULIN

1935 ◽  
Vol 19 (1) ◽  
pp. 95-108 ◽  
Author(s):  
Michael Heidelberger ◽  
Kai O. Pedersen
Keyword(s):  
Molecular Weight ◽  
Isoelectric Point ◽  
Specific Volume ◽  
Sedimentation Equilibrium ◽  
Sedimentation Constant ◽  
Diffusion Constants ◽  
Equilibrium Data ◽  
Round Numbers ◽  
And Diffusion

1. The sedimentation constant of hog thyroglobulin is 19.2ċ10–13. That of human thyroglobulin is essentially the same. 2. The specific volume of hog thyroglobulin is 0.72. 3. The isoelectric point of native hog thyroglobulin is at pH 4.58, that of denatured thyroglobulin at pH 5.0. 4. The molecular weight of hog thyroglobulin is, in round numbers, 700,000, as calculated from the sedimentation and diffusion constants, or 650,000, as calculated from the sedimentation equilibrium data. 5. The thyroglobulin molecule deviates markedly from the spherical.

STUDIES ON ϵ-PROTOTOXIN OF CLOSTRIDIUM PERFRINGENS TYPE D

1964 ◽  
Vol 42 (4) ◽  
pp. 545-554 ◽  
Author(s):  
A. F. S. A. Habeeb
Keyword(s):  
Clostridium Perfringens ◽  
Moving Boundary ◽  
Deae Cellulose ◽  
Paper Electrophoresis ◽  
Disc Electrophoresis ◽  
Type D ◽  
Sedimentation Constant ◽  
Diffusion Constants ◽  
Starch Gel ◽  
And Diffusion

Purified prototoxin of Clostridium perfringens type D was separated by column chromatography on CM-cellulose or DEAE-cellulose into two and three fractions respectively. The fractions exhibited prototoxin activity and showed immunochemical identity. The purified prototoxin gave a single component in the ultracentrifuge with a sedimentation constant of 2.85 S. The molecular weight was 25,100 ± 1500 and 23,200 when determined by the Archibald method and from sedimentation and diffusion constants respectively. Although the prototoxin was homogeneous by paper electrophoresis and moving boundary electrophoresis at pH 4.5, its heterogeneity was demonstrated on moving boundary electrophoresis at pH 8.6; 72% of material had a mobility of −1 × 10−5 cm2/v sec and 28% with a mobility of −2.7 × 10−5 cm2/v sec. The electrophoretic heterogeneity was also demonstrated on starch gel and disc electrophoresis. Amino acid analysis showed the presence of hydroxyproline and four uncommon amino acids; two of the latter were identified tentatively as hydroxylysine and allohydroxylysine.

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