Effect Of Various Anions Research Articles

A Synthetic Hydrogel with Thermoreversible Gelation. Ii. Effect of Added Salts

Abstract The sol-gel transition temperature of a thermoreversible hydrogel composed of poly (N-isopropylacrylamide)-b-poly(ethylene glycol) was determined from dynamic viscoelastic measurement. The sol-gel transition temperature was affected by the amount and sort of added salts. With increasing salt concentration, salts with a salting-out nature decreased the sol-gel transition temperature whereas salts with a salting-in nature increased the sol-gel transition temperature. The effect of various anions on the sol-gel transition temperature was interpreted by their influence on the hydrophobic effect.

Effect of various anions on the stepwise melting of plasmid DNA.

Differential scanning calorimetry (DSC) was carried out for the study on the effect of various anions on the melting of plasmid pJL3-TB5 DNA (5, 277 base pairs in length). In the presence of halide ions such as Cl-, Br-, or I- in citrate buffer solutions, seven separate peaks caused by the stepwise melting of the DNA molecule were found in the DSC curve. Similar profile of the DSC curve was also found in the presence of SCN-. Such a characteristic melting profile was not observed, when some other buffer solutions such as phosphate, borate, and acetate buffers were used. These ions affected significantly the melting profile of DNA; the height of the peaks seen in the high temperature range decreased and broadened. The presence of the anions such as NO3-, ClO4-, SO42- and IO3- instead of Cl- in the saline-sodium citrate (SSC) buffer solution also affected the DSC curves in the high temperature range in the similar manner to phosphate, borate, and acetate buffers. These results indicate that the type of anions in the solution as well as that of cations is very important for the melting of DNA. Since anions are known to alter the structure of water, it is suggested that these results are closely related to alteration of the structure of water caused by the interaction between anions and water, rather than the direct interaction between anions and DNA. The borate buffer solutions also showed not only clearly separated peaks, but also excellent reversibility for the melting of the DNA.

Effect of Anions on Photosystem 1-Mediated Electron Transport in Spinach Chloroplasts

The effect of various anions on photosystem I (PSI)-mediated electron transport was studied in control and heat-treated chloroplasts. Results show that heat treatment exposes not only some of the reduced dichlorophenolindophenol binding sites, but also certain anion binding sites. Moreover, the site of action of anions is at two places in the electron transport chain: one site is between the DCMU binding site and the HgCl 2 binding site (on plastocyanin) and the other is on the P700 itself

Anion-induced conformational change of apo-electron-transferring flavoprotein.

Apoprotein of electron-transferring flavoprotein (ETF) exists in an equilibrium between two different forms, only one of which can associate with FAD (Sato, K. et al. (1991) J. Biochem. 109, 734-740), as represented in the following kinetic scheme: A* in equilibrium with A, A+FAD in equilibrium with holoETF, where "A*" and "A" are the different forms of apoETF. In the present study, the effects of various anions on the conversion between the two forms of apoETF were investigated by kinetic analyses on binding of FAD to apoETF. All the anions tested here induced the conversion from "A*" to "A"; the order of the effectiveness was I- approximately Br- greater than Cl- greater than F-. Further, glycerol also induced the conversion from "A*" to "A". The elution pattern of apoETF on molecular sieve chromatography was changed by addition of salts or glycerol; this change was due to the conversion from "A*" to "A" by the added solutes. The "A*" form was eluted more rapidly than the "A" form, indicating that the "A*" form exists in a looser conformation than the "A" form. The far-UV CD spectral change upon addition of salts indicated that a greater part of the secondary structure is retained in the conversion from "A*" to "A," but the "A" form contains a somewhat larger amount of beta-sheet than "A*."

The effects of adsorbed anions on the oxidation of D-glucose on gold single crystal electrodes

The effects of various anions on the oxidation of glucose on single crystal gold electrodes were studied in HClO 4, CF 3SO 3H, HNO 3, H 2SO 4, H 3PO 4 and HCl solutions. Contrary to common belief, glucose can be oxidized on gold in acid solutions, but only in the absence of strongly adsorbed anions such as chlorides, sulfates and phosphates. The reaction is partly or completely inhibited in solutions containing specifically adsorbed anions. The data show some indication of an (OH) ads layer on gold at potential cathodic to +1.2 V vs rhe in HClO 4 and CF 3SO 3H solutions. Based on the rates of oxidation of glucose, the following sequence has been found for the inhibition of the glucose oxidation by adsorbed anions: ClO − 4 ≈ CF 3SO − 3 ⪡ NO − 3 ⪡ HSO − 4 (SO 2− 4) < H 2PO − 4 (HPO 2− 4 < Cl −.

Anion and pH-dependent conformational transition of an amphiphilic polypeptide

While several proteins, including β-lactamase, cytochrome c and apomyoglobin, are maximally unfolded at pH 2 by HCl in the absence of salt, the addition of anions, either from salt or acid, co-operatively induces the unfolded proteins to refold to a molten globule state, because anions bind preferentially to the compact molten globule state compared to the extended unfolded state. To study the role of the anion-dependent conformational transition at neutral pH, we synthesized a model polypeptide of 51 amino acid residues, consisting of tandem repeats of a Lys-Lys-Leu-Leu sequence and containing a turn sequence, Asn-Pro-Gly, at the center of the molecule. The model polypeptide showed no significant conformation by circular dichroism under conditions of low salt at neutral pH. However, addition of anions, either from salt or acid, induced the folding transition to an α-helical conformational state. The order of effectiveness of various anions in inducing the folding transition was consistent with the series of anions in inducing the molten globule of the acid-denatured protein. This suggests that the helical state of the model polypeptide is equivalent to the molten globule state. At pH values above 9, the model polypeptide also took an α-helical conformation, which was very similar to that induced by anions. On the basis of the chloride and pH-dependent conformational transitions, a phase diagram for the conformational states was constructed. The phase diagram was explained simply by assuming that the conformational transition is linked to the proton and the anion bindings to a limited number of amino groups and that anions bind only to the protonated groups.

Relationship Between the HSAB Principle and Effects of Various Anions and a Tetra‐n‐butylammonium Ion on Passive Film of Iron in a Borate Buffer Solution

Effects of various anions on the passive current density and pitting potential of an iron electrode in a borate buffer solution at pH 8.49 were discussed on the basis of the hard and soft acids and bases principle (HSAB principle). The effect of anion on the passive current density was confirmed to be closely related to the HSAB principle. This result implies that the anion classified as a hard base is adsorbed with less difficulty on the passive film than that of a soft base. A group of anions I−, Br−, Cl−, and S2− at of the concentration shifted the pitting potential toward a negative potential, being aggressive upon the passivity of iron. The breakdown of passive film occurs more readily by the action of anion classified as a harder base in this group. Anions F−, , , , , , CN−, and , belonging to another group, scarcely induce the breakdown of a passive film at . The anions of the former group were detected near the iron substrate in the passive film, but those of the latter were observed only at the film surface by XPS measurements. A cation, tetra‐n‐butylammonium ion inhibited the passive current density and the breakdown of passive film in the presence of the added anions.

Effects of various anions on the Raman spectrum of halorhodopsin

Resonance Raman experiments were conducted to probe and understand the effect of various anions on halorhodopsin. These included monoatomic anions Cl- and Br-, which bind to the so-called halorhodopsin binding sites I and II, and polyatomic anions NO3- and ClO4-, which bind to site I only. The two types of ions clearly show different effects on the vibrational spectrum of the chromophore. The differences are not localized to the Schiff base region of the molecule, but extend to the chromophore structure-sensitive fingerprint region as well. We find that the protonated Schiff base frequency is at 1,633 cm-1 for Cl- and Br- ions, as reported previously for Cl-. However, we find that two Schiff base frequencies characterize halorhodopsin upon binding of the polyatomic anions. One frequency lies at the same location as that found for the monoatomic anions and the other is at 1,645 cm-1. Halorhodopsin with bound NO3- and ClO4- thus may consist of two heterogeneous structures in equilibrium. This heterogeneity does not seem to correlate with a retinal isomeric heterogeneity, which we can also demonstrate in these samples. The results suggest that anions binding to site I do not bind to the Schiff base directly, but can influence chromophore and/or protein conformational states.

Synergic extraction of Pr(III), Ho(III) and Er(III) with a mixture of 2-thenoylltrifluoroacetone and tribenzylamine

Synergic solvent extraction of Pr(III), Ho(III) and Er(III) was carried out at pH≤3.5 with a mixture of 2-thenoyltrifluoroacetone (HTTA) and tribenzylamine (TBA) from perchlorate media, having ionic strength 0.1M(H+, ClO 4 − ). The stoichiometmric composition of all three synergic adducts was established to be Pr(TTA)3·3TBA, Ho(TTA)3·3TBA and Er(TTA)3·3TBA. The formation constants KTTA and Ksyn and stability constant ±syn were also computed and found to be in the order Er≥Ho>Pr. The effect of various anions on the extraction has also been studied.

The effects of various anions and cations on the regulation of pyruvate dehydrogenase complex activity from pig kidney cortex.

The activity of pyruvate dehydrogenase complex (PDC) purified from pig kidney cortex was found to be affected by various uni- and bi-valent ions. At a constant strength of 0.13 M at pH 7.8, K+, Na+, Cl-, HCO3- and HPO4(2-) had significant effects on the activity of PDC: Na+, K+ and HPO4(2-) stimulated, but HCO3- and Cl- inhibited. The stimulatory effect of Na+ was mediated by a change in the Vmax. of PDC only, whereas K+ produced an increase in Vmax. and a change in the Hill coefficient (h). The extent of stimulation produced by HPO4(2-)4 on the activity of PDC was dependent on the concentrations of K+ and Na+. Both cations at concentrations higher than 40 mM partially prevented the effect of HPO4(2-)4. Cl- and HCO3- anions decreased the Vmax. of the enzyme and increased the S0.5 for pyruvate. The effects of Na+, K+, Cl-, HPO4(2-) and HCO3- on the activity of PDC were additive. In the presence of 80 mM-K+, 20 mM-Na+, 10 mM-HPO4(2-), 20 mM-Cl- and 20 mM-HCO3- the activity of PDC was increased by 30%, the S0.5 for pyruvate was increased from 75 to 158 microM and h was decreased from 1.3 to 1.1. Under these conditions and at 1.0 mM-pyruvate, the activity of PDC was 80% of the maximal activity achieved in the presence of these ions and 4.5 mM-pyruvate. The present study suggests that PDC may operate under non-saturating concentrations for substrate in vivo.

Ionic dependence of bumetanide binding to the rabbit parotid Na/K/Cl cotransporter.

The Na/K/Cl-dependent component of the binding of the loop diuretic bumetanide to basolateral membrane vesicles from the rabbit parotid is studied. A Scatchard analysis indicates that this binding is due to a single high-affinity site with KD = 3.2 +/- 0.3 microM (n = 9) at 100 mM sodium, 100 mM potassium and 5 mM chloride. When KCl-dependent 22Na transport and tracer [3H]-bumetanide binding are monitored simultaneously as a function of (unlabeled) bumetanide concentration it is found that the K0.5 for bumetanide inhibition of both processes are identical indicating that the high-affinity bumetanide binding site studied here is identical with a bumetanide-inhibitory site on the Na/K/Cl cotransport system previously identified in this preparation (R.J. Turner. J.N. George and B.J. Baum, J. Membrane Biol. 94:143-152, 1986). High-affinity bumetanide binding exhibits a hyperbolic dependence on both [Na] and [K] consistent with Na/bumetanide and K/bumetanide binding stoichiometries of 1:1 and K0.5 values of approximately 33 mM for sodium and 23 mM for potassium. In contrast, the dependence on [Cl] is biphasic, with bumetanide binding increasing from 0 to 5 mM chloride and decreasing toward baseline levels thereafter. Scatchard analysis of this latter inhibitory effect of chloride indicates a competitive interaction with bumetanide in agreement with earlier indications that bumetanide inhibits Na/K/Cl cotransport at a chloride site. However, studies of the effects of various anions on bumetanide binding and 22Na transport show a poor correlation between the specificities of these two processes, suggesting that the inhibitory chloride site is not a chloride transport site.

Participation of water in conformational change of isotactic poly(2‐hydroxyethyl methacrylate) as studied by viscometry in various electrolytic solutions

AbstractConformational properties of isotactic poly(2‐hydroxyethyl methacrylate) (PHEMA) have been studied by viscometry in various electrolytic solutions. The intrinsic viscosity of isotactic PHEMA at 0.01M salt solution increases with decreasing the B coefficient in Jones—Dole's equation. In respective to water structures, a polymer chain is more expanded in the salt solution including water structure breaker ions. As the concentration of ions increases, the interactions between polymer segments and ions make a major contribution to conformational changes of isotactic PHEMA. Depending on the kind of ions, a salting‐in or out effect is observed at higher concentrations than 0.1M salt solution. We observed that the denaturing effects of various anions in isotactic PHEMA salt solutions are as follows; SO42‐ &lt; F− &lt; I− NO3− &lt; SCN‐. This order is similar to the Hofmeister series. To investigate the influences of denaturing agents on solvent structures, we also compared the guanidine hydrochloride effect with the tetrabutylammonium chloride effect in isotactic PHEMA solution.

Effect of Various Anions and Zwitterions on the Lasing Properties of a Photostable Cationic Laser Dye

An unusually photostable cationic laser dye first prepared by quaternization of the free base 4PyMPO (Figure 1) with methyl p-toluenesulfonate unexpectedly had, when flashlamp pumped in methanol, half the energy output of four other N-methyl quaternary salts: the methanesulfonate, the trifluoromethanesulfonate, the perchlorate, and the tetrafluoroborate. When four homologous zwitterions (Figure 2) prepared from 4PyMPO were tested in methanol, the output energies ranged from 1.4 to 2.5 times that of the p-toluenesulfonate, and up to 1.3 times that of the salt with the highest output. When flashlamp pumped in water, the zwitterions showed 1.5 to 2.0 times the output energy of the p-toluenesulfonate in water. Many of the dyes displayed laser output curves that were split in the middle, so that lasing energy appeared on either side of a dark valley. Among the zwitterions, a regular shifting from red to blue was observed as the carbon chain length was increased.

Intramitochondrial location and some characteristics of chicken liver aspartate aminotransferase

1. 1. Chicken liver mitochondrial aspartate aminotransferase was found to be located in the intermembrane space and bound to the inner mitochondrial membrane. 2. 2. Purification of two mitochondrial fractions containing aspartate aminotransferase activity was performed. Both fractions showed similar chromatographic behaviour and identical isoelectric point and molecular weight values. 3. 3. There were no significant differences in the general kinetic mechanism, K m values, substrates inhibition and effect of various anions on the activity of mitochondrial aspartate aminotransferase purified from both fractions.

The synergistic effect of anions and the ammonium cation on the inhibition of iron corrosion in acid solution

The synergistic effect of various anions and the tetra- n-butylammonium cation on the inhibition of iron corrosion in 1 M HClO 4 and their joint adsorption on iron were studied by using an impedance and a polarization technique. Surface coverage obtained from double layer capacitance showed joint adsorption of the anion and cation on the iron surface. Assuming competitive adsorption of these ions at the interface, the synergism of corrosion inhibition and joint adsorption were estimated using a parameter calculated from the inhibition efficiencies and the surface coverages of the anion and/or cation. The synergistic effect was shown for all of the anions and cation examined.

Thin-layer chromatography of phenyl thiohydantoin derivatives of amino acids on silica gel thin layers impregnated with zinc salts and some metal sulphates.

Thin-layer chromatography of fifteen-component mixtures of phenyl thiohydantoin derivatives of amino acids was carried out on silica gel plates impregnated with various Zn salts (chloride, sulphate, phosphate and acetate) and sulphates of Mg, Mn, Fe and Co, and three solvent systems were developed. The effect of various anions and cations on the chromatographic behaviour is discussed.

LITERATURE ABSTRACTS

GENERAL PRINCIPLES: The Development of An Inexpensive Pressure Transducer for Use at the Denture Base‐Mucosal Surface Interface. C. J. Watson and M. D. Abdul Wahab GENERAL PRINCIPLES: Jaw Opening Forces in Human Subjects. P. Sharkey, D. K. Boyle, R. Orchardson and D. A. McGowan GENERAL PRINCIPLES: Effects of Various Anions on the Rheological and Gelling Behavior of Soy Proteins: Thermodynamic Observations. M. Babajimopoulos, S. Damodaran, S. S. H. Rizvi and J. E. Kinsella GENERAL PRINCIPLES: Relaxation Behavior of Elastomers Under Large Deformation. N. Nakajima and E. R. Harrell GENERAL PRINCIPLES: A New Empirical Model to Simulate Transient Shear Stress Growth in Semi‐Solid Foods. P. L. Mason, K. L. Bistany, M. G. Puoti and J. L. Kokini GENERAL PRINCIPLES: Rheology and Microstructure of Dispersions and Solutions of the Microbial Polysaccharide from Xan thomonas campestris (xanthan gum). V. J. Morris, D. Franklin and K. I'Anson GENERAL PRINCIPLES: Some Theoretical Rheological Characteristics of the Mechanical Signals in Sensory Evaluation of Texture. M. Peleg GENERAL PRINCIPLES: Predicting the Texture of Liquid and Melting Semi‐Solid Foods. J. L. Kokini and E. L. Cussler GENERAL PRINCIPLES: Restructured Red Meat Products; In Review. S. C. Seideman and P. R. Durland GENERAL PRINCIPLES: Possible Role of Muscle Proteins on Flavor and Tenderness of Meat. A. M. Perirson, A. M. Wolzak and J. I. Gray GENERAL PRINCIPLES: Methods for Analysing the Breakdown of Food in Human Mastication. F. W. Lucas and D. A. Luke GENERAL PRINCIPLES: Computer Simulation of the Breakdown of Carrot Particles during Human Mastication. P. W. Lucas and D. A. Luke INSTRUMENTATION &amp; METHODOLOGY: Response of Moderately Concentrated Xanthan Gum Solutions to Time‐Dependent Flows Using Two‐Color Flow Birefringence. A. W. Chow and G. G. Fuller INSTRUMENTATION &amp; METHODOLOGY: Gel Photoelasticity in the Design and Interpretation of Penetrometer Tests. D. Kilcast, M. M. Boyer and J. C. Fry INSTRUMENTATION &amp; METHODOLOGY: Experiences Gained With INSTRON‐1140 Universal Texture Measuring Instrument. Gy. Beke, A. Sebok and Gy. Schlotter OBJECTIVE MEASUREMENTS: Heat‐Induced Changes in the Texture of Carrots. M. Horvath‐Mosonyi and L. Horvath OBJECTIVE MEASUREMENTS: Determination of Maturity in Apricots by Instrumental Measurement of Flesh Firmness and Colour. C. Varady‐Burgetti, J. Hamori‐Szabo and E. Faskerti SENSORY EVALUATION: Effects of Color on Aroma, Flavor and Texture Judgments of Foods. C. M. Cliristensen SENSORY EVALUATION: Psychophys ical Threshold Level of Periodontal Mechanoreceptors in Man. D. Van Steenberghe and J. H. de Vries FACTORS AFFECTING TEXTURE: The Consistency of Butter IV Improvement of the Physical Quality of Summer Butter with Special Reference to the Fat Content of Buttermilk on the Basis of Crystallization Curves. E. Frede, D. Precht and K. H. Peters FACTORS AFFECTING TEXTURE: A New Type of Semi‐hard Cheese from Recombined Milk. A.A. Hofi, M.N.I. Magdoub, B. Laila, Abd'El Homid and SH. G. Osmon FACTORS AFFECTING TEXTURE: A Study of the Effects of Frozen Storage on Certain Functional Properties of Meat and Fish Protein. F. Jimenez Colmenero and A. J. Borderias FACTORS AFFECTING TEXTURE: Extrusion of Defatted Soy Flour‐Hydrocolloid Mixtures. Effect of Operating Parameters on Selected Textural and Physical Properties. G. Boison, M. V. Taranto and M. Cheryan FACTORS AFFECTING TEXTURE: A Laboratory Microwave Sterilizer and Its Possible Application Toward Improving Texture of Sterilized Vegetables. J. Loh and W. M. 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Anion effects on the liver alcohol dehydrogenase reaction

The effects of various anions on the rate constant for dissociation of NADH from a binary complex with horse liver alcohol dehydrogenase were evaluated. Phosphate, sulfate, and fluoride had no effect, while nitrate and the other halide ions caused a three- to fourfold increase in the rate constant for NADH dissociation. These results indicate that a ternary enzyme-NADH-anion complex is formed, and from the anion concentration dependence the relative affinities are iodide > nitrate and bromide > chloride. At high salt concentrations, above 0.2 m, the rate constants for NADH dissociation decreased, which was attributed to a decrease in the activity coefficient of the reactants or “salting in.” The rate constant for NADH dissociation from ternary complex with imidazole, which crystallizes in an orthorhombic form rather than triclinic, was also substantially enhanced by anions. This provides an indication that the enhancement is independent of the conformational state of the enzyme complex. Thus, the most likely explanation for the observed enhancement of NADH dissociation is anion interference with binding of the coenzyme pyrophosphate group, which does not occur with larger anions such as phosphate or sulfate. Since NADH dissociation partially limits the turnover of the enzyme, the effect of nitrate on steady-state turnover was determined. A twofold increase was observed at optimal levels of nitrate, at both substrate inhibitory and noninhibitory concentrations of ethanol.

Effect of various anions on the stability of the coiled coil of skeletal muscle myosin.

The stability of skeletal myosin rod was studied by following the dependence of both papain digestion kinetics and helix-coil transition temperatures on the concentration of neutral salts. The rate of papain-catalyzed digestion of rod to form subfragment 2 and light meromyosin was strongly dependent on chloride concentration but essentially independent of acetate concentration up to 2.0 M. The rod exhibited a biphasic melting curve in 0.6 M NaCl, 5 mM phosphate, and 0.1 mM ethylenediaminetetraacetic acid (EDTA), pH 7.3, with transitions at 45 and 53 degrees C. In 0.6 M CH3COONa, 5 mM phosphate, and 0.1 mM EDTA, pH 7.3, the transitions occurred at 50 and 58 degrees C, respectively. Transition temperatures were obtained with a novel curve-fitting method. The effect of increasing chloride ion concentration on melting profiles was 2-fold. Below 0.6 M salt, the two transition temperatures, Tm,1 and Tm,2, depended on salt concentration such that increasing NaCl concentration caused a small stabilization of the helix while increasing acetate concentration caused the helix to become markedly more stable. Between 0.6 and 1.0 M, variation of chloride concentration had almost no effect on the thermal stability of the rod while increasing acetate concentration increased its stability considerably. Above 1.0 M NaCl, the melting profiles became broad with a third transition being observed (e.g., at 3.0 M, Tm,3 = 38 degrees C), indicating the existence of a region which has a tendency to be destabilized by chloride. The third transition was not observed at comparable concentrations of acetate. This effect of chloride was not expected on the basis of its position in the Hofmeister series.(ABSTRACT TRUNCATED AT 250 WORDS)

Interaction between anions and the reduced folate/methotrexate transport system in L1210 cell plasma membrane vesicles: directional symmetry and anion specificity for differential mobility of loaded and unloaded carrier.

The effect of various anions on the mediated influx and efflux of [3H]methotrexate by L1210 cell plasma membrane vesicles in a HEPES buffer system was studied. Our results show that flux is stimulated to the same extent in either direction when SO4, Pi, or folate compounds (1,L5-CHO-folate-H4, methotrexate), but not Cl- was present in the opposite compartment. This implies the property of directional symmetry, a condition in which differential mobility of loaded and unloaded carriers occurs in both directions. We also observed a similarity in the specificity of the interaction between various anions and carrier in each orientation of the membrane, in the order, Cl- much less than Pi approximately equal to SO2-4 much less than methotrexate less than 1,L5-CHO-folate-H4. Also, the absolute differential in mobility of loaded and unloaded carrier (assumed from the extent of transstimulation obtained) varied substantially among the anions examined. No stimulation was obtained with Cl-, and stimulation was twofold with Pi, SO2-4 and methotrexate and fourfold with 1,L5-CHO-folate-H4. Transstimulation of flux from either external or internal compartment only occurred when a positive gradient of total anions was maintained in the opposite compartment. Also, no stimulation occurred when the same equivalence of two different anions are present in opposing compartments. The concentration of anions required to transstimulate [3H]methotrexate influx was increased four- to 10-fold when vesicles were equilibrated in 145 mM NaCl.(ABSTRACT TRUNCATED AT 250 WORDS)