Equilibrium sedimentation profile of dilute, salt-free charged colloids

2008 ◽  
Vol 129 (20) ◽  
pp. 204504 ◽  
Author(s):  
Tzu-Yu Wang ◽  
Hsien-Tsung Li ◽  
Yu-Jane Sheng ◽  
Heng-Kwong Tsao
Keyword(s):  
Sedimentation Profile ◽  
Charged Colloids ◽  
Equilibrium Sedimentation

Sedimentation of charged colloids in the gravitational field : Relaxation toward equilibrium

2000 ◽  
Vol 10 (PR5) ◽  
pp. Pr5-109-Pr5-112
Author(s):  
J.-F. Dufrêche ◽  
J.-P. Simonin ◽  
P. Turq
Keyword(s):  
Gravitational Field ◽  
Charged Colloids

Characterization and Partial Purification of Heterodisperse Polysomal RNAs in Normal and Neoplastic Cells

1972 ◽  
Vol 58 (2) ◽  
pp. 71-94
Author(s):  
Ada Sacchi ◽  
Gianni Chinali ◽  
Susetta Pons ◽  
Michela Galdieri ◽  
Piero Cammarano
Keyword(s):  
Size Distribution ◽  
Density Gradient ◽  
Rat Liver ◽  
Sucrose Density Gradient ◽  
Partial Purification ◽  
Messenger Rnas ◽  
Alkaline Ph ◽  
Sedimentation Profile ◽  
Molecular Weights ◽  
Phenol Extraction

The size distribution of cytoplasmic messenger RNAs (m-RNA) has been studied in rat liver and in monodifferentiated cells (mouse reticulocytes and myelomas). It has been found that the RNA which exhibits a « rapid turnover » and a polydisperse profile of radioactivity is refractory to phenol extraction. This property has been exploited to selectively isolate m–RNA from the phenol residue by means of an extraction at an alkaline pH. The sucrose density gradient profiles of m–RNA isolated from monodifferentiated cells show monodisperse peaks having the sedimentation coefficients expected on the basis of the molecular weights of monocistronic messages for α and β chains of hemoglobin (reticulocytes) and L and H chains of immunoglobulin (myelomas). The sedimentation profile of cytoplasmic m–RNA associated with rat liver polysomes shows a much broader distribution, with sedimentation coefficients ranging from 8 S to 28 S.

scholarly journals Crystallization and reentrant melting of charged colloids in nonpolar solvents

2015 ◽  
Vol 91 (3) ◽  
Author(s):  
Toshimitsu Kanai ◽  
Niels Boon ◽  
Peter J. Lu ◽  
Eli Sloutskin ◽  
Andrew B. Schofield ◽  
...  
Keyword(s):  
Charged Colloids ◽  
Nonpolar Solvents

scholarly journals The association behaviour of β-lactamases. Sedimentation equilibrium studies in ammonium sulphate solutions

1986 ◽  
Vol 237 (2) ◽  
pp. 511-517 ◽  
Author(s):  
E H Braswell ◽  
J R Knox ◽  
J M Frère
Keyword(s):  
Equilibrium Constants ◽  
Solubility Limit ◽  
Sedimentation Equilibrium ◽  
Association Model ◽  
Sodium Cacodylate ◽  
Dimerization Constant ◽  
Equilibrium Studies ◽  
Crystal Forms ◽  
Beta Lactamases ◽  
Equilibrium Sedimentation

The beta-lactamases (EC 3.5.2.6) from TEM plasmid RP4, Bacillus licheniformis 749/C and Enterobacter cloacae P99 were studied in solution over a wide concentration range by equilibrium sedimentation. Though crystal symmetries indicate that all three enzymes are potentially dimeric in their crystal forms, in 50 mM-sodium cacodylate at pH 6.5 the enzymes show only a small tendency to associate, indicated by a weight-average Mr (Mw) at 3% (w/v) concentration about 9% greater than that of the monomer. Although the mode of association could not be determined, this extent of association corresponded to a dimerization constant of about 2 × 10(2) M-1. In 2.1 M-(NH4)2SO4 the B. licheniformis enzyme shows some association at concentrations over 1%, displaying an Mw value at 7% concentration about 60% more than the monomer. Under the same conditions Mw for the Entero. P99 enzyme is about 60% greater than the monomer near the solubility limit of about 2%. However, the Mw for the TEM enzyme is over twice that of the monomer at its solubility limit (3%) in 1.7 M-(NH4)2SO4. Fitting the sedimentation data of the TEM enzyme in 1.7 M-(NH4)2SO4 with a dimerization model and an indefinite-isodesmic-association model yielded equilibrium constants of 1.5 × 10(4) and 3.3 × 10(2) M-1 respectively, with the indefinite-isodesmic model giving the better fit. Fitting the data for the other two enzymes yielded values of 1.4 × 10(3) and 1.7 × 10(2) M-1 respectively for the Entero. P99 enzyme and 4.5 × 10(2) and 45 M-1 respectively for the B. licheniformis enzyme. It could not be determined which model was the better fit for these two enzymes. Since none of the beta-lactamases studied here showed strong evidence of the terminal aggregate being a dimer, we conclude that crystalline dimers, if they exist, will not be tightly associated or physiologically significant.

scholarly journals Direct Measurement of Three-Body Interactions amongst Charged Colloids

2004 ◽  
Vol 92 (7) ◽  
Author(s):  
Matthias Brunner ◽  
Jure Dobnikar ◽  
Hans-Hennig von Grünberg ◽  
Clemens Bechinger
Keyword(s):  
Direct Measurement ◽  
Charged Colloids ◽  
Three Body

scholarly journals Does high-mobility-group non-histone protein HMG 1 interact specifically with histone H1 subfractions?

1979 ◽  
Vol 183 (3) ◽  
pp. 657-662 ◽  
Author(s):  
P D Cary ◽  
K V Shooter ◽  
G H Goodwin ◽  
E W Johns ◽  
J Y Olayemi ◽  
...  
Keyword(s):  
Specific Interaction ◽  
High Mobility ◽  
Histone H1 ◽  
High Mobility Group ◽  
Chromosomal Protein ◽  
Histone Protein ◽  
Total Histone ◽  
Equilibrium Sedimentation ◽  
Histone H5

The interaction of the non-histone chromosomal protein HMG (high-mobility group) 1 with histone H1 subfractions was investigated by equilibrium sedimentation and n.m.r. sectroscopy. In contrast with a previous report [Smerdon & Isenberg (1976) Biochemistry 15, 4242–4247], it was found, by using equilibrium-sedimentation analysis, that protein HMG 1 binds to all three histone H1 subfractions CTL1, CTL2, and CTL3, arguing against there being a specific interaction between protein HMG 1 and only two of the subfractions, CTL1 and CTL2. Raising the ionic strength of the solutions prevents binding of protein HMG 1 to total histone H1 and the three subfractions, suggesting that the binding in vitro is simply a non-specific ionic interaction between acidic regions of the non-histone protein and the basic regions of the histone. Protein HMG 1 binds to histone H5 also, supporting this view. The above conclusions are supported by n.m.r. studies of protein HMG 1/histone H1 subfraction mixtures. When the two proteins were mixed, there was little perturbation of the n.m.r. spectra and there was no evidence for specific interaction of protein HMG 1 with any of the subfractions. It therefore remains an open question as to whether protein HMG 1 and histone H1 are complexed together in chromatin.

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