Dynamics of single polyelectrolyte chains in salt-free dilute solutions investigated by analytical ultracentrifugation

2015 ◽  
Vol 17 (24) ◽  
pp. 15896-15902 ◽  
Author(s):  
Zhonglin Cao ◽  
Sha Wu ◽  
Guangzhao Zhang
Keyword(s):  
Analytical Ultracentrifugation ◽  
Complex Dynamics ◽  
Electrostatic Repulsion ◽  
Dilute Solution ◽  
Dilute Solutions

Two concentration regimes are distinguished in polyelectrolyte salt-free dilute solution. The complex dynamics of polyelectrolytes arises due to the interchain electrostatic repulsion.

The use of methyl green as a histochemical reagent

1965 ◽  
Vol s3-106 (73) ◽  
pp. 3-13
Author(s):  
JOHN R. BAKER ◽  
ELIZABETH G. M. WILLIAMS
Keyword(s):  
Connective Tissue ◽  
Malachite Green ◽  
Helix Aspersa ◽  
Common Snail ◽  
Methyl Green ◽  
Dilute Solution ◽  
Dilute Solutions ◽  
The Common ◽  
Snail Helix Aspersa

The cation of methyl green carriea two poaitive charges, that of malachite green only one; but the two dyes behave towards tissue-constituents in almost exactly the same way. These dyes are not specific for chromatin. They colour certain objects that are devoid of DNA, even when they are used in very dilute solution. The granules of cells called Körnchenzellen in the connective tissue of the common snail, Helix aspersa, are strongly coloured by both dyes from very dilute solutions, and thus provide a striking instance of the unspecificity of these dyes. Malachite green, which is stable and free from contamination by metachromstic impurities, can advantageously replace the methyl green commonly used in mixtures with pyronine. It is suggested that pyronine may have a greater capacity for penetrating into close-textured objects, such ss nucleoli and ribosomes, than methyl and malachite greens.

The Adaptation of Gunda Ulvae to Salinity

1931 ◽  
Vol 8 (1) ◽  
pp. 82-94
Author(s):  
C. F. A. PANTIN
Keyword(s):  
Osmotic Pressure ◽  
Electric Conductivity ◽  
Fresh Water ◽  
Salt Concentration ◽  
Sea Water ◽  
Distilled Water ◽  
Dilute Solution ◽  
Dilute Solutions ◽  
The Moment ◽  
Limiting Value

1. The rate of loss of salts by the estuarine worm, Gunda ulvae, on transference from sea water to various dilute solutions has been studied by measurement of the electric conductivity of the solutions. 2. Salts are lost by the worms from the moment of immersion in dilute solutions. Conditions affecting the rate of loss of salts are discussed. 3. The relation between the amount of salts lost and the total electrolyte content of the worm was determined. It is shown that the worms only lose 25 per cent. of their salts during the time that they imbibe a volume of water from the dilute solution equal to their initial volume. 4. The limiting internal salt concentration of worms surviving in waters containing calcium is about 6-10 per cent. of the normal concentration in sea water. No such limiting value can be found for distilled water, since salts are lost continuously till cytolysis occurs. The significance of the limiting concentration is discussed. 5. The effect of osmotic pressure, pH, dilute solutions of NaCl, NaHCO3, glycerol, CaCl2 and CaCO3 are studied. The presence of calcium reduces the rate of loss of salts. Other factors do not seem to influence this rate. 6. The relation of calcium to the maintenance of normal permeability to water and salts in the worm, and the significance of this to the problem of migration into fresh water are discussed.

scholarly journals ACTION OF FORMALDEHYDE ON ENZYMES AND ON CERTAIN PBOTEIDS

1899 ◽  
Vol 4 (1) ◽  
pp. 47-80 ◽  
Author(s):  
C. L. Bliss ◽  
F. G. Novy
Keyword(s):  
Room Temperature ◽  
Dilute Solution ◽  
Cent Solution ◽  
Dilute Solutions ◽  
Moderate Amount ◽  
Strong Concentration ◽  
Preceding Work ◽  
Micro Organisms ◽  
Short Time ◽  
Sufficient Concentration

The following general conclusions may be drawn from the preceding work: Fibrin is altered by formaldehyde and is then less easily digested by pepsin and by trypsin. Papaïn is apparently unable to digest fibrin even when this is exposed to very weak formaldehyde (1:1000) for a very short time. The casein of milk, on contact with formaldehyde, undergoes rapid alteration and is as a result not coagulated by rennet, or but very slowly. Such altered casein, like similar fibrin, is not readily digested by the proteolytic ferments. The longer the formaldehyde acts on casein and on fibrin the more marked is the result. Pepsin is not affected by a one per cent solution of formaldehyde, even when the mixture has stood for four weeks. Even a five per cent solution of formaldehyde acting for three weeks has no effect on pepsin. Contrary results obtained by others are due to an alteration of the fibrin by the formaldehyde. A putrid solution of pepsin in distilled water one month old digests fibrin as readily as a fresh solution. Rennet is not affected even by a four per cent solution of formaldehyde acting for several weeks. The absence of coagulation at times is due to the action of formaldehyde on the casein of the milk and not on the rennet ferment. Papaïn is very quickly altered by formaldehyde, even in very dilute solution. Moreover, it is unable to digest fibrin that has been exposed to the action of a very dilute solution of formaldehyde for a short time. Trypsin is altered by formaldehyde to such an extent that digestion of fibrin will not take place, or but very slowly. The extent to which trypsin is affected by formaldehyde depends largely upon the amount of organic matter present, as well as on the amount of ferment in the solution. Amylopsin is not destroyed by very dilute solutions of formaldehyde, but stronger solutions decrease the activity of the ferment, and if used in sufficient concentration will destroy it completely. Ptyalin, like the diastatic ferment of the pancreas, is not destroyed by dilute solutions of formaldehyde. If the latter is used in rather strong concentration and allowed to act for some time it will destroy the ferment. The action of formaldehyde is more rapid and more marked at a slightly elevated temperature than at ordinary room temperature. Malt diastase, unlike the diastatic ferments of the saliva and pancreatic solution, is not destroyed by formaldehyde when this is used in moderate amount and at ordinary temperature. Unlike pepsin, a solution of malt diastase readily undergoes decomposition on standing even for one or more days. This destruction is undoubtedly due to bacteria since it does not take place when formaldehyde is present. Consequently the favoring action which formaldehyde apparently exerts on diastase really consists in the inhibition of the growth of micro-organisms, and hence the diastase is protected against decomposition.

A METHOD OF ISOLATION OF PROTEINS FROM DILUTE SOLUTIONS

1957 ◽  
Vol 35 (1) ◽  
pp. 63-70 ◽  
Author(s):  
T. Webb ◽  
A. H. Sehon ◽  
B. Rose
Keyword(s):  
Chloride Solution ◽  
Sodium Chloride Solution ◽  
Protein Solutions ◽  
Low Molecular Weight ◽  
Simultaneous Removal ◽  
Dilute Solution ◽  
Dilute Solutions ◽  
Total Recovery ◽  
Electrophoretic Patterns ◽  
Normal Human

A method has been developed for the concentration of dilute solutions of biocolloids. It consists of the removal of water by pervaporation and the simultaneous removal of salts and other low molecular weight materials by dialysis. A dilute solution of serum (2 ml. of serum per liter of 0.9% sodium chloride solution) of known composition was used to test the efficacy of the method. The electrophoretic patterns of the reconstituted serum protein solutions were compared with those of the untreated sera. The total recovery of biocolloids from such solutions was about 73% and the electrophoretic patterns obtained were similar to those of the untreated sera. The method is reasonably simple, rapid, and compares favorably with other methods used for the concentration of biocolloids. It has also been employed in the concentration of biocolloids of normal human urine.

scholarly journals The dynein light chain 8 (LC8) binds predominantly “in-register” to a multivalent intrinsically disordered partner

2020 ◽  
Vol 295 (15) ◽  
pp. 4912-4922 ◽  
Author(s):  
Patrick N. Reardon ◽  
Kayla A. Jara ◽  
Amber D. Rolland ◽  
Delaney A. Smith ◽  
Hanh T. M. Hoang ◽  
...  
Keyword(s):  
Light Chain ◽  
Intrinsically Disordered Proteins ◽  
Analytical Ultracentrifugation ◽  
Complex Dynamics ◽  
Regulatory Protein ◽  
Disordered Proteins ◽  
Dynein Light Chain ◽  
Linker Length ◽  
Intrinsically Disordered ◽  
Wide Range

Dynein light chain 8 (LC8) interacts with intrinsically disordered proteins (IDPs) and influences a wide range of biological processes. It is becoming apparent that among the numerous IDPs that interact with LC8, many contain multiple LC8-binding sites. Although it is established that LC8 forms parallel IDP duplexes with some partners, such as nucleoporin Nup159 and dynein intermediate chain, the molecular details of these interactions and LC8's interactions with other diverse partners remain largely uncharacterized. LC8 dimers could bind in either a paired “in-register” or a heterogeneous off-register manner to any of the available sites on a multivalent partner. Here, using NMR chemical shift perturbation, analytical ultracentrifugation, and native electrospray ionization MS, we show that LC8 forms a predominantly in-register complex when bound to an IDP domain of the multivalent regulatory protein ASCIZ. Using saturation transfer difference NMR, we demonstrate that at substoichiometric LC8 concentrations, the IDP domain preferentially binds to one of the three LC8 recognition motifs. Further, the differential dynamic behavior for the three sites and the size of the fully bound complex confirmed an in-register complex. Dynamics measurements also revealed that coupling between sites depends on the linker length separating these sites. These results identify linker length and motif specificity as drivers of in-register binding in the multivalent LC8–IDP complex assembly and the degree of compositional and conformational heterogeneity as a promising emerging mechanism for tuning of binding and regulation.

Equilibrium size distribution and phase separation of multivalent, molecular assemblies in dilute solution

Soft Matter ◽  
2020 ◽  
Vol 16 (23) ◽  
pp. 5458-5469 ◽  
Author(s):  
Dan Deviri ◽  
Samuel A. Safran
Keyword(s):  
Phase Separation ◽  
Size Distribution ◽  
Self Assembly ◽  
Dilute Solution ◽  
Lattice Animals ◽  
Dilute Solutions ◽  
Molecular Assemblies ◽  
Equilibrium Size

Equilibrium self-assembly, gelation, and phase separation of multivalent molecules in dilute solutions analyzed using statistics of lattice animals depicted here.

The reactions of hydrazines with trans-Dichlorobis(ethylenediamine)cobalt(III)chloride, and the isolation and kinetic studies of a Chlorobis(ethylenediamine)methylhydrazinecobalt(III) isomer

1973 ◽  
Vol 26 (9) ◽  
pp. 1923 ◽  
Author(s):  
SC Chan ◽  
CK Lee
Keyword(s):  
Electron Transfer ◽  
Kinetic Studies ◽  
Intramolecular Electron Transfer ◽  
Dilute Solution ◽  
Dilute Solutions ◽  
Spectroscopic Observations ◽  
Acid And Base ◽  
Concentrated Solution ◽  
Kinetics Of ◽  
Hydrolysis Of

The reactions of hydrazine, methylhydrazine, and 1,1-dimethylhydrazine with trans-dichlorobis(ethylenediamine)cobalt(III) chloride in concentrated and dilute solutions are studied. In concentrated solution, there is a reduction by hydrazine to form the insoluble polymeric [CoII(N2H4)2Cl2]n, a substitution by methylhydrazine to form chlorobis(ethylenediamine)methylhydrazinecobalt(III) chloride, and a disproportionation with 1,1-dimethylhydrazine to form tris(ethylenediamine)cobalt(III) chloride. In dilute solution, the reaction observed is a hydroxide substitution by hydrolysis of 1,1- dimethylhydrazine, a reduction to soluble cobalt(II)-ethylenediamine species with hydrazine, and a mixture of both processes for methylhydrazine. The chlorobis(ethylenediamine)methylhydrazinecobalt-(III) chloride obtained is a new complex, and is assigned a cis configuration on the basis of spectroscopic observations. The kinetics of its intramolecular electron-transfer, as well as its acid and base hydrolyses are also studied.

scholarly journals Interaction parameters of oxygen and deoxidants in liquid iron

2016 ◽  
Vol 52 (1) ◽  
pp. 41-46 ◽  
Author(s):  
e Costa
Keyword(s):  
Liquid Iron ◽  
Atomic Number ◽  
Thermodynamic Modeling ◽  
Calphad Method ◽  
Interaction Parameters ◽  
Heats Of Formation ◽  
Dilute Solution ◽  
Dilute Solutions ◽  
Interaction Coefficients ◽  
Computational Tools

During decades before the evolution of more powerful computational tools, simplified formalisms such as the Wagner dilute solution formalism, have been successfully used in the study of deoxidation reactions of steel. This formalism relies on the introduction of interaction coefficients to account from deviations from Henry?s Law. With the evolution of thermodynamic modeling and of the CALPHAD method, the fact that thermodynamic descriptions using these parameters were derived to be used at relatively dilute solution has been sometimes overlooked and the formalism has been criticized for deviating from reality in non-dilute solutions. In this work, it is shown that the interaction parameters used in this formalism correlate with properties of the solutes and of the solvent. The work focuses on the interactions in systems Fe-M-O, where M is a deoxidant. Correlations between interaction coefficients and heats of formation of the corresponding oxides and with the atomic number of the deoxidants are demonstrated. This not only helps supporting the physicochemical soundness of the formalism but also provides a way of checking the consistency of data presented in this formalism.

scholarly journals TRANSPORT OF WATER FROM CONCENTRATED TO DILUTE SOLUTIONS IN CELLS OF NITELLA

1949 ◽  
Vol 32 (4) ◽  
pp. 559-566 ◽  
Author(s):  
W. J. V. Osterhout
Keyword(s):  
Osmotic Pressure ◽  
Living Cells ◽  
The Other ◽  
Fundamental Importance ◽  
Dilute Solution ◽  
Cell Water ◽  
Dilute Solutions ◽  
The Difference ◽  
In Cells

The transport of water from concentrated to dilute solutions which occurs in the kidney and in a variety of living cells presents a problem of fundamental importance. If the cell acts as an osmometer we may expect to bring about such transport by creating an inwardly directed osmotic drive which is higher in one part of the cell than in other regions of the same cell. The osmotic drive is defined as the difference between internal and external osmotic pressure. Experiments with Nitella show that this expectation is justified. If water is placed at one end of the cell (A) and 0.4 M sucrose with an osmotic pressure of 11.2 atmospheres at the other end (B) water enters at A, passes along inside the cell, and escapes at B leaving behind at B the solutes which cannot pass out through the protoplasm. Hence the internal osmotic pressure becomes much higher at B than at A. When 0.4 M sucrose at B is replaced by 0.3 M sucrose with an osmotic pressure of 8.1 atmospheres we find that water enters at B, passes along inside the cell, and escapes at A so that water is transported from a concentrated to a dilute solution although the difference in osmotic pressure of the 2 solutions is more than 8 atmospheres. The solution at B thus becomes more concentrated. It is evident that if metabolism produces a higher osmotic pressure and consequently a higher inwardly directed osmotic drive in one region of the cell as compared with other parts of the same cell water may be transferred from a concentrated to a dilute solution so that the former solution becomes still more concentrated.

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