Solubility In Salt Solutions Research Articles

Artificial neural network modelling for solubility of carbon dioxide in various aqueous solutions from pure water to brine

Predicting the solubility of CO2 in various aqueous solutions, such as pure water, brackish water, saline water and brine, has become increasingly important because of the interdisciplinary significance of carbon dioxide solubilization, particularly in the energy and environmental fields. Despite experimental difficulties, the solubility of CO2 in various aqueous solutions of single and multi-salt was measured under limited conditions for specific purposes. In this study, artificial neural network (ANN) model was applied to the solubility data of CO2 (2406 experimental data) in salt-dissolved solutions over a wide range of pressures (0.92–712.31 bar), temperatures (273.15–473.65 K), concentrations of electrostricted water molecules (0–90.12 mol/kgw), and overall mole fractions of dissolved salts (0–25.39 mol%), including supercritical condition of CO2. Compared with the conventional thermodynamic models using many parameters, the accuracy of ANN model with only four input variables was comparable for salt solutions and even feasible for brine-rock systems. While the average of the absolute relative deviation of the thermodynamic model with respect to CO2 solubility data in pure water and single-salt solution (1556 data of total 2406 data) was 5.44 %, that of the developed ANN model for the corresponding data was 4.90 %. The developed ANN model presented the capability of dimensional extrapolation in the prediction of CO2 solubility in salt solutions without over-fitting when the thermodynamic-based input variable was used. The model for the solubility prediction of non-polar gases in salt solutions could be a useful approach in complex salt solutions under a wide range of temperature and pressure.

Liquid-Liquid Phase Separation in Supermicrometer and Submicrometer Aerosol Particles.

ConspectusThe interactions of aerosol particles with light and clouds are among the most uncertain aspects of anthropogenic climate forcings. The effects of aerosol particles on climate depend on their optical properties, heterogeneous chemistry, water uptake behavior, and ice nucleation activity. These properties in turn depend on aerosol physics and chemistry including composition, size, shape, internal structure (morphology), and phase state. The greatest numbers of particles are found at small, submicrometer sizes, and the properties of aerosol particles can differ on the nanoscale compared with measurements of bulk materials. As a result, our focus has been on characterizing the phase transitions of aerosol particles in both supermicrometer and submicrometer particles. The phase transition of particular interest for us has been liquid-liquid phase separation (LLPS), which occurs when components of a solution phase separate due to a difference in solubilities. For example, organic compounds can have limited solubility in salt solutions especially as the water content decreases, increasing the concentration of the salt solution, and causing phase separation between organic-rich and inorganic-rich phases. To characterize the systems of interest, we primarily use optical microscopy for supermicrometer particles and cryogenic-transmission microscopy for submicrometer particles.This Account details our main results to date for the phase transitions of supermicrometer particles and the morphology of submicrometer aerosol. We have found that the relative humidity (RH) at which LLPS occurs (separation RH; SRH) is highly sensitive to the composition of the particles. For supermicrometer particles, SRH decreases as the pH is lowered to atmospherically relevant values. SRH also decreases when non-phase-separating organic compounds are added to the particles. For submicrometer particles, a size dependence of morphology is observed in systems that undergo LLPS in supermicrometer particles. In the limit of slow drying rates, particles <30 nm are homogeneous and larger particles are phase-separated. This size dependence of aerosol morphology arises because small particles cannot overcome the activation barrier needed to form a new phase when phase separation occurs by a nucleation and growth mechanism. The inhibition of LLPS in small particles is observed for mixtures of ammonium sulfate with single organic compounds as well as complex organics like α-pinene secondary organic matter. The morphology of particles affects activation diameters for the formation of cloud condensation nuclei. These results more generally have implications for aerosol properties that affect the climate system. In addition, LLPS is also widely studied in materials and biological chemistry, and our results could potentially translate to implications for these fields.

Transforming protein-polymer conjugate purification by tuning protein solubility

Almost all commercial proteins are purified using ammonium sulfate precipitation. Protein-polymer conjugates are synthesized from pure starting materials, and the struggle to separate conjugates from polymer, native protein, and from isomers has vexed scientists for decades. We have discovered that covalent polymer attachment has a transformational effect on protein solubility in salt solutions. Here, protein-polymer conjugates with a variety of polymers, grafting densities, and polymer lengths are generated using atom transfer radical polymerization. Charged polymers increase conjugate solubility in ammonium sulfate and completely prevent precipitation even at 100% saturation. Atomistic molecular dynamic simulations show the impact is driven by an anti-polyelectrolyte effect from zwitterionic polymers. Uncharged polymers exhibit polymer length-dependent decreased solubility. The differences in salting-out are then used to simply purify mixtures of conjugates and native proteins into single species. Increasing protein solubility in salt solutions through polymer conjugation could lead to many new applications of protein-polymer conjugates.

Interaction of hepatic chromatin with androgen-receptor complex.

When the chromatin prepared from male rat livers interacted with [3H] testosterone-receptor complex prepared from male rat livers, the binding was much higher than when interacted with free [3H] testosterone, indicating that the formation of testosterone-receptor complex is prerequisite for interaction with chromatin. When the [3H] testosterone-receptor complex was interacted with the chromatin and the bound chromatin proteins were extracted into three fractions based on their extractability or solubility in salt solutions, higher radioactivities were found in the 0.35 M NaCl-extract and 2.0 M NaCl residual fraction. Chromatin was fractionated into 0.35 M NaCl-soluble, 2.0 M NaCl-soluble and insoluble fractions, and interaction of free [3H] testosterone or [3H] testosterone-receptor complex with chromosomal fractions was studied. The binding of the chromosomal fractions with free [3H] testosterone was negligible compared with that of [3H] testosterone-receptor complex. The binding of 0.35 M NaCl-soluble fraction with [3H] testosterone-receptor complex was higher than that of 2.0 M NaCl-soluble fraction. The binding ability of 2.0 M NaCl-insoluble fraction with [3H] testosterone-receptor complex was twice as much as that of the intact chromatin. This observation indicated that salt-soluble fractions of chromatin contributes only partly to the binding of chromatin with [3H] testosterone-receptor complex and that other components in 2.0 M NaCl-insoluble fraction may participate in the binding.

Salts, Interfacial Water and Protein Conformation

ABSTRACTA phenomenological theory of salt-induced Hofmeister phenomena is presented, based on a relation between protein solubility in salt solutions and protein-water interfacial tension. As a generalization of previous treatments, it implies that both kosmotropic salting-out and chaotropic salting-in are manifested via salt-induced changes of the hydrophobic/hydrophilic properties of protein-water interfaces. The theory is applied to describe the salt-dependent free energy profiles of proteins as a function of their water-exposed surface area. On this basis, three classes of protein conformation have been distinguished. The new formalism accounts for the diverse manifestations of salt effects on protein conformation, dynamics and stability, and resolves the puzzle of chaotropes stabilizing certain proteins (and other anomalies). It is also shown that the relation between interfacial tension and protein structural stability is straightforwardly linked to protein conformational fluctuations, providing a keystone for the microscopic interpretation of Hofmeister effects. Implications of the results concerning the use of Hofmeister effects in the experimental study of protein function are discussed.

Interfacial Water Structure Controls Protein Conformation

A phenomenological theory of salt-induced Hofmeister phenomena is presented, based on a relation between protein solubility in salt solutions and protein-water interfacial tension. As a generalization of previous treatments, it implies that both kosmotropic salting out and chaotropic salting in are manifested via salt-induced changes of the hydrophobic/hydrophilic properties of protein-water interfaces. The theory is applied to describe the salt-dependent free energy profiles of proteins as a function of their water-exposed surface area. On this basis, three classes of protein conformations have been distinguished, and their existence experimentally demonstrated using the examples of bacteriorhodopsin and myoglobin. The experimental results support the ability of the new formalism to account for the diverse manifestations of salt effects on protein conformation, dynamics, and stability, and to resolve the puzzle of chaotropes stabilizing certain proteins (and other anomalies). It is also shown that the relation between interfacial tension and protein structural stability is straightforwardly linked to protein conformational fluctuations, providing a keystone for the microscopic interpretation of Hofmeister effects. Implications of the results concerning the use of Hofmeister effects in the experimental study of protein function are discussed.

Salt Effects on an Ion–Molecule Reaction—Hydroxide-Catalyzed Hydrolysis of Benzocaine

This work investigates the effect of various salts on the rate of a reaction involving a neutral species (benzocaine alkaline hydrolysis). Benzocaine hydrolysis kinetics in NaOH solutions in the presence of different salts were studied at 25 degrees C. Benzocaine solubility in salt solutions was also determined. Solubility data were used to estimate salt effects on benzocaine activity coefficients, and pH was used to estimate salt effects on hydroxide activity coefficients. Salts either increased or decreased benzocaine solubility. For example, solubility increased with 1.0 M tetraethylammonium chloride (TEAC) approximately 3-fold, whereas solubility decreased approximately 35% with 0.33 M Na2SO4. Salt effects on hydrolysis rates were more complex and depended on the relative magnitudes of the salt effects on the activity coefficients of benzocaine, hydroxide ion, and the transition state. As a result, some salts increased the hydrolysis rate constant, whereas others decreased it. For example, the pseudo-first-order rate constant decreased approximately 45% (to 0.0584 h(-1)) with 1 M TEAC, whereas it increased approximately 8% (to 0.116 h(-1)) with 0.33 M Na2SO4. Different salt effects on degradation kinetics can be demonstrated for a neutral compound reacting with an ion. These salt effects depend on varying effects on activity coefficients of reacting and intermediate species.

Gilthead seabream (Sparus aurata): suitability for freezing and commercial alternatives

AbstractThe quality of portion‐size farmed gilthead seabream (Sparus aurata) during frozen storage and the influence of post‐mortem treatments were studied in order to find new ways of marketing this species. Portion‐sized gilthead seabream, fasted for 48 h prior to slaughter, were frozen and stored at −20 °C for up to one year. Whole fish were frozen immediately after rigor mortis; gutted fish were frozen immediately after rigor and after 5 days of storage in ice. All lots were stored at −20 °C for up to one year. The myofibrillar protein of this species was very stable and a slight decrease of solubility in salt solutions was found only after one year of frozen storage. A slight decrease in water‐holding capacity and a slight increase in shear strength were observed, but these were lower than in other species. These changes were reflected as increased toughness and reduced juiciness in sensory analysis of the cooked fillets after one year. The main changes in the cooked fillets were observed in odour and flavour. No significant detrimental effect due to the guts was detected during frozen storage. Storage in ice prior to freezing was reflected in sensory assessment of the raw fish, mainly in terms of initial higher demerit points for fishy odour, gills and eyes; however, no effect was observed in the cooked fillets. Copyright © 2004 Society of Chemical Industry

Solubility and crystallization of xylose isomerase from Streptomyces rubiginosus

We have studied the crystallization and crystal solubility of xylose isomerase (XI) from Streptomyces rubiginosus. In this paper, we show a rational approach for developing a large-scale crystallization process for XI. Firstly, we measured the crystal solubility in salt solutions with respect to salt concentration, temperature and pH. In ammonium sulfate the solubility of XI decreased logarithmically when increasing the salt concentration. Surprisingly, the XI crystals had a solubility minimum at low concentration of magnesium sulfate. The solubility of XI in 0.17 M magnesium sulfate was less than 0.5 g l −1. The solubility of XI increased logarithmically when increasing the temperature. We also found a solubility minimum around pH 7. This is far from the isoelectric point of XI (pH 3.95). Secondly, based on the solubility study, we developed a large-scale crystallization process for XI. In a simple and economical cooling crystallization of XI from 0.17 M magnesium sulfate solution, the recovery of crystalline active enzyme was over 95%. Moreover, we developed a process for production of uniform crystals and produced homogenous crystals with average crystal sizes between 12 and 360 μm.

Proteolytic activity of four strains of Pseudomonas on crude extracts of contractile proteins

Hydrolytic activities of exogenous proteases obtained from Pseudomonas upon crude extracts of contractile proteins were studied. Four strains were used: C61 and C20, isolated from beef samples, and P. fragi (ATCC-4973) and P. fluorescens (NRRL-B-1244). Proteolytic activity was tested on crude extracts of actomyosin, myosin+ actin+regulatory proteins, actin and high molecular weight proteins obtained from postrigor beef by differential precipitation according to their solubility in salt solutions of various ion strengths. Electrophoresis analysis showed considerable degradation of actomyosin in samples treated with a C61 enzymatic extract. Myosin degradation was similar for treatments with proteases obtained from C61 and P. fragi. Actin degradation was similar for all enzymatic extracts. The most active protease was a 46.8 kDa enzyme produced by C60. P. fragi produced two proteases of 49.2 kDa and 34.2 kDa, P. fluorescens one of 46.1 kDa, and C20 one of 49.2 kDa.

Peroxidase: Changes in soluble and bound forms during maturation and ripening of apples.

Peroxidase (POD) enzymes, both soluble and bound, have been implicated in the ripening process of a number of fruits. However, their roles are poorly understood. The aim of this study was to define clearly the classes of POD activity in apple parenchyma tissues on the basis of their solubility in salt solutions, to determine the subcellular localisation of ionically-bound POD activity, and to determine whether soluble- or ionically-bound POD activities exhibit any relationships with maturation and ripening. The cortical parenchyma of apples (Malus domestica Borkh cv. Cox's orange pippin) was investigated for changes in POD activity during maturation and post-harvest storage at 0, 4, and 8°C at 100% relative humidity (RH), and controlled atmosphere (CA) storage (4°C in 1.25% O2 and 0.5% CO2 ). The parenchyma cells contained both soluble and ionically-bound POD activity. The ionically-bound POD was located in the cell wall in the middle lamella, plasmodesmata and cell corners, and could be extracted quantitatively with 0.4 M CaCl2 at neutral pH to leave a POD-free residue. During maturation, both forms of activity increased on a 'per apple' basis, but decreased as a function of fresh weight. Under all conditions of storage, soluble POD exhibited a peak of activity at approximately the mid-point of ripening-related softening; this event may constitute a biochemical marker. In contrast, ionically-bound POD generally decreased during ripening, except under CA storage. CA storage inhibited ripening-related softening after an initial loss of firmness. However, softening resumed after transfer of apples to normal atmosphere storage at 8°C. This may provide a new insight into controlling tissue softening.

Protein salting-out: Phase equilibria in two-protein systems

The phase behavior of two aqueous binary protein mixtures, lysozyme-chymotrypsin and lysozyme-ovalbumin, was determined in ammonium sulfate solutions. Protein concentrations were determined in both phases as a function of pH and ionic strength. For lysozyme-chymotrypsin mixtures, the observed phase behavior was similar to that for each individual protein; the presence of the second protein had little influence. The phase behavior of lysozyme-ovalbumin mixtures, however, was different from that of the respective single-protein systems. Lysozyme and ovalbumin are found together in egg whites; their association is both pH and ionic-strength dependent. The association of proteins is a key determinant of protein solubility in salt solutions.

Mild Chemical Deglycosylation of Horseradish Peroxidase Yields a Fully Active, Homogeneous Enzyme

Horseradish peroxidase isoenzyme C (HRP) contains eight N-linked glycans composed of Man, Xyl, Fuc, and GlcNAc. These glycans were resistant to enzymatic hydrolysis by endoglycosidases peptide-N4-(N-acetyl-β-glucosaminyl)asparagine amidase F, endo-β-N-acetylglucosaminidase H, and endo-b-N-acetylglucosaminidase F under conditions where ovalbumin was deglycosylated. However, using anhydrous trifluoromethanesulfonic acid (TFMS) in the presence of 90 mM phenol for 5 min at −10°C, all carbohydrate except GlcNAc was removed. Sixty percent of deglycosylated HRP was active after this TFMS treatment. Benzhydroxamic acid affinity chromatography separated active and inactive deglycosylated HRP. TFMS treatment, however, introduced negative charges in all inactive HRP and in about 90% of the active deglycosylated HRP. The nature of this modification has not been identified. After ion-exchange chromatography, homogeneous and fully active deglycosylated HRP, showing the original pI of 9, electronic absorption spectrum, and enzyme kinetics, was obtained. In this purified product no amino acid modifications were detected by amino acid analysis, partial sequencing, and mass spectrometry of tryptic peptides. The deglycosylated product showed greatly reduced solubility in salt solution compared to that of authentic HRP.

Aggregation and secondary structure of synthetic amyloid βA4 peptides of Alzheimer's disease

The deposition of amyloid βA4 in the brain is a major pathological hallmark of Alzheimer's disease. Amyloid βA4 is a peptide composed of 42 or 43 amino acid residues. In brain, it appears in the form of highly insoluble, filamentous aggregates. Using synthetic peptides corresponding to the natural βA4 sequence as well as analog peptides, we demonstrate requirements for filament formation in vitro. We also determine aggregational properties and the secondary structure of βA4. A comparison of amino-terminally truncated βA4 peptides identifies a peptide spanning residues 10 to 43 as a prototype for amyloid βA4. Infrared spectroscopy of βA4 peptides in the solid state shows that their secondary structure consists of a β-turn flanked by two strands of antiparallel β-pleated sheet. Analog peptides containing a disulfide bridge were designed to stabilize different putative β-turn positions. Limited proteolysis of these analogs allowed a localization of the central β-turn at residues 26 to 29 of the entire sequence. Purified βA4 peptides are soluble in water. Size-exclusion chromatography shows that they form dimers that, according to circular dichroism spectroscopy, adopt a β-sheet conformation. Upon addition of salts, the bulk fraction of peptides precipitates and adopts a β-sheet structure. Only a small fraction of peptides remains solubilized. They are monomeric and adopt a random coil conformation. This suggests that the formation of aggregates depends upon a hydrophobic effect that leads to intra- and intermolecular interactions between hydrophobic parts of the βA4 sequence. This model is sustained by the properties of βA4 analogs in which hydrophobic residues were substituted. These peptides show a markedly increased solubility in salt solutions and have lost the ability to form filaments. In contrast, the substitution of hydrophilic residues leads only to small deviations in the shape of filaments, indicating that hydrophilic residues contribute to the specificity of interactions between βA4 peptides.

Incorporation of [3H]leucine into an actin-like protein in response to 1,25-dihydroxycholecalciferol in chick intestinal brush borders.

1,25-Dihydroxycholecalciferol very rapidly stimulates the incorporation of [4,5-3H]leucine into at least two proteins of the chick intestinal mucosal cells. The smaller of the two proteins has mol.wt. approx. 42000, very similar to actin. Other properties of this protein were investigated, including its solubility in salt solution and its behaviour on gel electrophoresis and isoelectric focusing, and in all cases the 1,25-dihydroxycholecalciferol-stimulated protein was indistinguishable from intestinal actin. It was also shown that the brush borders of mucosal cells contain both beta- and gamma-actin in approximately equal amounts and that both forms of the protein appear to be affected by the hormone. It is concluded therefore that one of the earliest actions of 1,25-dihydroxycholecalciferol is to stimulate the incorporation of leucine into beta- and gamma-actin of the mucosal cells or into two proteins very like them.

Properties of carbohydrate-stripped thyroglobulin III. solubility characteristics of thyroglobulin

In studying the solubility characteristics of thyroglobulin, it was found that the removal of sialic acid residues from either human or hog thyroglobulin by treatment with neuraminidase markedly decreased the solubility in salt solutions. On the other hand, naturally sialic acid-rich thyroglobulin obtained from human diffuse goiter was slightly more soluble than thyroglobulin in which sialic acid content was within the normal range. However, the desialized preparations prepared from both normal and sialic acid-rich thyroglobulin showed markedly lower solubility and further, showed no significant difference in solubility between them. These results indicate that the surface charge of thyroglobulin which influenced the salting-out property depends largely on the number of sialic acid residues in a thyroglobulin molecule, not on the degree of iodination of thyroglobulin.

The synthesis of poly(acrylic acid hydrazide) and poly(methylacrylic acid hydrazide) and their reaction products with ribonucleoside dialdehydes

Atactic and syndiotactic poly(acrylic acid hydrazide) and atactic, syndiotactic and isotactic poly(methylacrylic acid hydrazide) have been reacted with the di-aldehydes derived from adenosine, guanosine, inosine, cytidine and uridine to give polymers each containing a single type of base residue. Not all of the hydrazide residues of the polymeric hydrazides reacted; guanosine dialdehyde gave the most reaction and inosine dialdehyde the least. Isotactic poly(methylacrylic acid hydrazide) was much less reactive than the other polymeric hydrazides. The adenine-containing and the cytosine-containing polymers with atactic backbones had a low solubility in water whereas those with syndiotactic backbones had a relatively high solubility. For a given polymeric hydrazide backbone the adenine-containing polymers were always the least soluble in water. Most of the ribonucleoside dialdehyde-containing polymers, with the exception of those containing uridine dialdehyde, had only a low solubility in salt solution (0.3M sodium chloride, 0.03M trisodium citrate). No evidence could be obtained for any interaction of these polymers with polynucleotides.

Quantitative determination of antibody-bound labeled antigens by filtration through cellulose porous membranes

A method based on the use of celullosic membranes of uniform pore size (Millipore filter) has been devised to separate and quantitative isotopically labeled antigens bound to antibody from free nonbound labeled antigens. In conditions under which variable amounts of I-125 bovine serum albumin (BSA) were added to a constant amount of rabbit IgG anti-BSA, the results throughout the antibody excess zone up to equivalence compare with those obtained by the labeled antigens quantitative precipitin reaction and by the precipitation of globulins with ammonium sulfate at 50% saturation. In the antigen excess zone a linear relationship was found between antibody-bound labeled BSA retained on the filter and rabbit IgG anti-BSA precipitated at equivalence. This technique has the disadvantage that the results, unlike those of the modified antigen-binding capacity (mABC, ref. 3), cannot be expressed on antibody weight estimates. Its advantages are: ( a) the separation of antibody-bound antigen from free antigen is accomplished in a single and reproducible step of 15 min, which eliminates time-consuming procedures, ( b) it is not dependent upon antigen solubility in salt solutions and may be used with antigens of different molecular weight and shape, e.g., BSA and human γ-globulin, and ( c) the sensitivity of this procedure, unlike that of the precipitin reaction, appears not to be limited by the solubility of the antigen/antibody aggregate.

A critical look at two objective tests for cold storage deterioration

SummaryProtein solubility in salt solutions and cell fragility are two possible measures of textural changes in cold stored fish. These measurements are discussed for a wide range of species. The discrepancies between the methods, the artefacts in measurement caused by proteolysis at higher temperatures and possibly by free fatty acid are considered. The effect of pH, horizontal and vertical strength of the myofibrils, and initial protein solubility on taste panel assessment are discussed.

Effect of in Vivo X-Irradiation on Nucleoprotein Stability

ABS>The deoxyribonucleoprotein and DNA isolated from radiosensitive tissues (thymus and spleen) of rats 24 hr after lethal whole-body irradiation were found to show changes in solubility in salt solutions of various ionic strengths. Changes in ease of deproteinization by detergent were also observed. No marked changes in these characteristics were noted in the DNP prepared from the radioresistant organs (liver and kidney) studied. These studies do not indicate whether these effects are autolytic or direct, however. (auth)