Effect Of Neutral Salts Research Articles

The effects of neutral salts on the conformational transition of ceruloplasmin

Neutral salts inhibit the activity of ceruloplasmin in an order of increasing effectiveness for anions as follows: ClO 4 − < Br − < Cl − < F − < SCN − < OCN − < N 3 − < CN −. Circular dichroism measurements show that, save CN −, this order parallels that of increasing effectiveness in inducing α-helix structure.

On Colloidal Ampholytes : The Effect of Neutral Salts on Isoionic Bovine Serum Albumin and the Dissociation Constant of its Carboxyl Groups between pH 2.0 and 5.0

On Colloidal Ampholytes : The Effect of Neutral Salts on Isoionic Bovine Serum Albumin and the Dissociation Constant of its Carboxyl Groups between pH 2.0 and 5.0

Effects of neutral salts on carbon and nitrogen mineralisation of organic matter in soil

In an incubation experiment the mineralisation of gulmohur (Delonix regia L.) leaves added to soil was studied at increased salt concentrations. CO2 evolution and total carbon mineralisation decreased with increased concentrations of salt mixture (NaCl+CaCl2) from 0.1 to 5.1 per cent, and the process of nitrification was completely inhibited between 0.6–0.9 per cent salt. The loss of nitrogen was about 10.4 per cent from control up to 0.6 per cent salt and about 17.8 per cent from 0.9 to 5.1 per cent salt. The formation of ammonium was of the same order of magnitude under all treatments. Extractable carbon varied between 27–32 per cent of the total carbon in the soil and humic/fulvic acid carbon ratio varied between narrow limits of 0.41–0.58 in saline and non-saline soils.

The effect of neutral salts on the conformational transition of poly-alpha-amino acids. I. Potentiometric titration and optical rotatory dispersion studies.

AbstractThe effect of salts on the coil‐to‐helix transition of poly‐α‐amino acids was investigated by optical rotatory dispersion and potentiometric titration techniques. Both charge‐dependent and charge‐independent contributions to the free energy were considered.The free energy of formation ΔF° of the uncharged α‐helix from the uncharged random coil for poly‐L‐glutamic acid (PGA) decreases very rapidly in the limit of zero added salt concentration. This effect probably depends on the uncertainty affecting the choice of the extrapolation of the apparent pK for the random coil at low ionic strength. Above 0.1 M salt, where the free energy determination becomes meaningful, the anions and cations investigated do not affect the value of ΔF°, with the exception of Li+. Our data support the point of view that this cation binds to the peptide group.A class of salts produces an increase of the helical content of poly‐L‐ornithine (PO) both at low and high degree of ionization. This effect appears to be anion dependent. It is shown that (1) no change of ΔF° is involved; (2) recent theories of polyelectrolyte solutions cannot account for our results. We suggest that a true site binding of the anions to the charged amino groups occurs. The role of electrostatic binding in determining the conformational stability of proteins in the presence of some anions is stressed, and a general treatment for the electrostatic binding equilibria is outlined.

Electrostatic Effects on the Oxidative Polymerization of 2, 6-Xylenol Catalyzed by Copper-Partially-quaternized Poly(vinylpyridine) Complexes

2, 6-Xylenol(XOH) was oxidatively polymerized by the Cu(II)-partially-quaternized poly (vinylpyridine) (QPVP) complexes in a homogeneous dimethylsulfoxide (DMSO) solution, and the electrostatic effects of the Cu-QPVP complex on the atalytic activity were discussed. The Cu-QPVP complex has a chelate structure in DMSO. The rate of polymerization of XOH by the Cu-QPVP catalyst was larger than that of the Cu-pyridine(Py) or the Cu-Poly(vinylpyridine) (PVP) catalyst. The results of the measurement of kinetic constants, the neutral salt effects and the infiuene of the monomer species, indicate that the higher activity of the CuQPVP catalyst was ascribed to the electrostatic action of the Cu-QPVP complex as a polycation. Moreover, the Cu-QPVP complex showed the higher catalytie activity when the degree of quaternization of QPVP was about 20-50. The catalytiactivity tends to become larger as increasing the degree of polymerization of QPVP.

Kinetic discussion on the catalysis of copper‐partially‐quaternized poly‐(vinylpyridine) complexes

Abstract2,6‐Xylenol was oxidatively polymerized by Cu‐poly (vinylpyridine) (PVP) complex or Cu‐partially‐quaternized PVP (QPVP) complex in a homogeneous dimethylsulfoxide solution, and the mechanism of the catalysis of the polymeric Cu complexes was discussed. The polymerization rate increased in the following order: Cu‐pyridine &lt;Cu‐PVP&lt;Cu‐QPVP. The catalytic activity of the Cu‐QPVP complex exhibited a maximum in the region where the percentage of quaternization of QPVP was 20‐50% and tended to increase with the degree of polymerization of QPVP. Considering through the kinetic constants of the polymerization, the neutral salt effect, and the influence of the monomer species, it was cleared that the higher activity of the Cu‐QPVP catalyst was attributed to the electrostatic interaction between the QPVP complex and the anionic monomer. That is to say, the intermediate complex, to which xylenol is coordinated, is enthalpically stabilized due to the electrostatic field of the QPVP complex. Activation entropy ΔS† of the polymer catalyst was larger in comparison with the monomeric analog, and the larger ΔS†S was observed in the PVP system and the neutral‐salt‐added QPVP system, of which structures were compact. It is considered that the frequency factor of the dissociation step of the activated monomer increases because of the high density of cupric ion in the polymer complex.

Effect of Neutral Salt on the Formation of Lysozyme-Substrate Complex

Effect of Neutral Salt on the Formation of Lysozyme-Substrate Complex

Neutral Salt Effect on the Interaction of Poly-α, l-glutamic Acid with Acridine Orange

Abstract The effect of potassium chloride on the absorption and optical rotatory properties of the poly-α,l-glutamic acid-acridine orange system in an aqueous solution was studied under various conditions. The stability of the helical conformation of poly-α,l-glutamic acid in this system was examined at different potassium chloride concentrations by estimating the helix fraction of the polymer. At pH 4.5, where poly-α,l-glutamic acid exists in the helix, it was found that the added potassium chloride raised the stability of the helical conformation of the polymer in this system. In this case, it was assumed that the added potassium chloride lowers the disturbance of helix formation by the bound acridine orange cation. However, when the solution’s pH was raised, the added potassium chloride lowered the extent of the helix fraction in this system. These phenomena were discussed on the basis of several experimental findings on the circular dichroism of the systems. Furthermore, from the change in the intensities of the circular dichroism with the variation in the potassium chloride concentration, it was presumed that the positive circular dichroism band at about 520 nm was due to the binding of dimeric acridine orange molecules to the polymer.

Conformational changes induced by the interaction of sodium dodecyl sulfate with bovine plasma albumin

The marked effects of neutral and acetate buffer salts on the difference spectra between bovine plasma albumin and the complex with sodium dodecyl sulfate or with sodium dodecanoate are observed. The binding of dodecyl sulfate with high affinity sites in bovine plasma albumin produces a large tyrosyl red shift and a small tryptophyl blue shift in 0.10 M KCl (pH 5.54) and a large tryptophyl blue shift in I = 0.10 sodium acetate buffer (pH 5.623). The 2H 2O perturbation spectra of the complexes with dodecyl sulfate in 0.10 M KCl do not show any changes in masking of tyrosyl and tryptophyl chromophores, up to the molar ratio of added dodecyl sulfate to bovine plasma albumin of 20. The complex of bovine plasma albumin with dodecanoate showes essentially similar results to those with dodecyl sulfate.

Model studies on the effects of neutral salts on the conformational stability of biological macromolecules. IV. Properties of fatty acid amide micelles.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTModel studies on the effects of neutral salts on the conformational stability of biological macromolecules. IV. Properties of fatty acid amide micellesAlberto Hamabata, Susan Chang, and Peter H. Von HippelCite this: Biochemistry 1973, 12, 7, 1278–1282Publication Date (Print):March 27, 1973Publication History Published online1 May 2002Published inissue 27 March 1973https://doi.org/10.1021/bi00731a006RIGHTS & PERMISSIONSArticle Views45Altmetric-Citations9LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (581 KB) Get e-Alerts Get e-Alerts

Model studies on the effects of neutral salts on the conformational stability of biological macromolecules. 3. Solubility of fatty acid amides in ionic solutions.

The solubilities of n-hexanamide, n-pentanamide, and n-butyramide in aqueous salt solutions are measured at several temperatures as a function of NaC104 and NaCl con- centrations (these salts representing, respectively, a strongly destabilizing and an essentially inert perturbant of macro- molecular stability). NaCl is found to be a more effective salting-out agent than NaC104 for all these amides, and thermodynamic parameters are derived for the transfer of each of these amides (at infinite dilution) from water to 1 M NaC104 or NaCl solutions. The free energy of transfer of a methylene group not directly adjacent to the amide dipole is shown to be a constant for each of these salt systems, corre-

Model studies on the effects of neutral salts on the conformational stability of biological macromolecules. I. Ion binding to polyacrylamide and polystyrene columns.

Model studies on the effects of neutral salts on the conformational stability of biological macromolecules. I. Ion binding to polyacrylamide and polystyrene columns.

Model studies on the effects of neutral salts on the conformational stability of biological macromolecules. II. Effects of vicinal hydrophobic groups on the specificity of binding of ions to amide groups.

Model studies on the effects of neutral salts on the conformational stability of biological macromolecules. II. Effects of vicinal hydrophobic groups on the specificity of binding of ions to amide groups.

Effect of anionic surfactants, nonionic surfactants and neutral salts on the conformation of spin-labeled erythrocyte membrane proteins

Erythrocyte membranes have been solubilized with anionic surfactants (sodium dodecyl sulfate and sodium deoxycholate), neutral salts (guanidine-HCl and KSCN), and a nonionic surfactant (Triton X-100). Conformational changes are observed by means of covalent attachment of N-(1-oxyl-2,2,6,6-tetramethyl-4-piperidinyl)maleimide to sulfhydryl groups of the membrane proteins. Conformational changes are produced by the anionic surfactants and neutral salts and are correlated with solubilization. Sodium dodecyl sulfate produces a unique effect; the conformational change lags the solubilization, and the threshold of the conformational change coincides with the critical micelle concentration. At concentrations giving partial solubilization, the conformation of the unsolubilized protein in the membrane is essentially identical with the conformation of the solubilized proteins. Superimposed spectra for a given agent have isoslopic points and suggest that solubilization with a particular agent may be a two-state process. Sodium dodecyl sulfate shows a third state at high concentrations. Conformational changes are not detected in protein solubilized by the nonionic surfactant.

Effect of alcohols and neutral salt on the thermal stability of soluble and precipitated acid-soluble collagen.

The effects of mono- and poly-hydric alcohols in the presence of KCl on the intrinsic stability of collagen molecules in dilute acid solution were compared with corresponding solvent and salt effects on the increased stability of the aggregated molecules in salt-precipitated fibrils. Salt addition decreased solubility and increased the thermal stability of fibrils, but progressively decreased the stability of collagen molecules in solution. In contrast, the alcohols enhanced solubility and decreased fibril stability, the effects increasing with solvent hydrocarbon chain length and with decreasing hydroxyl/methylene-group ratio. Molar destabilization of dissolved collagen by alcohols was lower than for fibrils, and at low salt concentration, both ethylene glycol and glycerol were structural stabilizers. Electron-micrograph studies indicated that salt-precipitated fibrils tended to adopt the native aggregation mode, and qualitatively similar solvent effects were observed in insoluble collagens. Implications of the experimental findings are discussed in terms of a model in which electrostatic and apolar interactions mainly govern the excess of stability in collagen fibrils whereas intrinsic stability of single molecules is a function of polar interactions and polypeptide-chain rigidity.

Effects of neutral inorganic salts on potentiometric titration curves of weak bases in nonaqueous solvents

Effects of neutral inorganic salts on potentiometric titration curves of weak bases in nonaqueous solvents

Neutral Salt Effects on Cationic Polymerization of N-Vinylcarbazole Initiated by Protonic Acids

Cationic polymerization of N-vinylcarbazole(VCZ) initiated by perchloric acid or trichloroacetic acid(TCA) in three different solvents(nitrobenzene(NB), ethylene dichloride(EDC), and benzene(Bz)) was studied at 30°C in the presence and absence of neutral electrolytes(tetra-n-butylammonium perchlorate(TBP) and tetraethylammonium perchlorate(TEP)). The kinetic quantity determined was the chain-transfer constant to methanol. Since chain-transfer constant is affected by the nature of kinetic chain carrier, the study of neutral salt effects on chain-transfer constants provides useful information on whether the cationic chain carrier is free or ion-paired. Measurements for six combinations of three solvents and two initiators either in the presence of TBP or in its absence afforded the following pieces of information.(1) The presence of TBP enhanced the chain-transfer constant in polar media. However, no neutral salt effects were observed in benzene, indicating that the growing carbonium ion in benzene is tightly ion-paired and the addition of TBP cannot affect the ionic association.(2) In EDC, the chain-transfer constants of methanol are very much enhanced by the addition of neutral electrolyte. The results were interpreted assuming that the rate of propagation decreases in the presence of TBP whereas the rate of chain-transfer reaction is relatively unaffected. A study of the deuterium isotope effect using methanol-d supports this view.(3) In NB, the propagating species in the absence of TBP seem to be free carbonium ions since the kind of initiator does not influence the chain-transfer constant. In this system, the growing cation would be strongly solvated and stabilized.(4) Dependence of the rate of polymerization on neutral salts was also investigated. The rate of polymerization is, however, a complex function of various rate constants and conclussion is difficult.Chain-transfer constants are very sensitive to the nature of propagating species and their determinations as functions of neutral electrolyte concentration would provide a useful procedure to study the ionic equilibria of the carbonium ion and ion pairs.

Effets de sels dans les milieux eau-dioxanne—I : Influence des sels sur la fonction d'acidité H 0 dans ces milieux

The effects of neutral salts on the indicator acidity function Ho have been studied in dioxane: water (40:60) and water. Acidity is strongly increased by salts. The effect is a specific one: the smaller the cation and the higher the charge the more the acidity increases. Some salts increase acidity more than strong acids. The observed differences have been explained by the solvation of the cations. The effects of salts are more important in dioxane water mixture than in water : dioxane is a “deaquate:”.

The effect of neutral salts on gelatin and peptides containing L-proline.

The effect of neutral salts on gelatin (heat denatured collagen) and peptides containing L-proline was studied by optical rotation and viscosity. The change of optical rotation of gelatin and peptides containing L-proline by various salts and denaturation reagents in water and nonaqueous solution was essentially the same as that of poly-L-proline, whereas L-proline suffered little effect from salts and reagents. Optical rotation of various peptides was measured in water and in 5M LiBr. Even dipeptides suffered the effect of salt. Decrease of specific levorotation by LiBr became larger as proline content increased, as peptides became longer and when N terminal was blocked with a benzyloxycarbonyl group. The change of optical rotation of gelatin was not sharp to be a cooperative phenomenon when salt concentration was varied. The change of viscosity of gelatin by salts was quite different from the change of optical rotation.

Kinetic Investigations of the Reaction of Brilliant Green with Alkalies. Influence of Ionic Strength

Abstract Kinetic studies of the reaction of brilliant green with alkalies have been made by following the reaction spectrophotometrically at 625 mμ. The reaction has been found to be bimolecular but under experimental condition of excess alkali, it obeyed a first order law. The rate constants was independent of the concentration of brilliant green but it varied linearly with the hydroxyl ion concentration. Effect of neutral salt on the rate of reaction was investigated in aqueous and in 40% acetone-water media. The rate was found to decrease progressively with increasing ionic strength in both media. Analysis of the data by Brφnsted-Christiansen-Scatchard equation yielded a value of −1 for ZaZb indicating thereby that the rate-determining step involves oppositely charged species possessing unit charge. The value of inoic interaction parameter, ai corresponded to 1.5 and 4.75 Å in aqueous and 40% acetone-water medium respectively. Without attaching too precise a meaning to ai it is suggested that B.G. ion is presumably solvated to a greater extent in 40% acetone-water than pure water.