Solutions Of Na Research Articles

Ion channel selectivity through ion-modulated changes of selectivity filter pKa values

In bacterial voltage-gated sodium channels, the passage of ions through the pore is controlled by a selectivity filter (SF) composed of four glutamate residues. The mechanism of selectivity has been the subject of intense research, with suggested mechanisms based on steric effects, and ion-triggered conformational change. Here, we propose an alternative mechanism based on ion-triggered shifts in pKa values of SF glutamates. We study the NavMs channel for which the open channel structure is available. Our free-energy calculations based on molecular dynamics simulations suggest that pKa values of the four glutamates are higher in solution of K+ ions than in solution of Na+ ions. Higher pKa in the presence of K+ stems primarily from the higher population of dunked conformations of the protonated Glu sidechain, which exhibit a higher pKa shift. Since pKa values are close to the physiological pH, this results in predominant population of the fully deprotonated state of glutamates in Na+ solution, while protonated states are predominantly populated in K+ solution. Through molecular dynamics simulations we calculate that the deprotonated state is the most conductive, the singly protonated state is less conductive, and the doubly protonated state has significantly reduced conductance. Thus, we propose that a significant component of selectivity is achieved through ion-triggered shifts in the protonation state, which favors more conductive states for Na+ ions and less conductive states for K+ ions. This mechanism also suggests a strong pH dependence of selectivity, which has been experimentally observed in structurally similar NaChBac channels.

Selectivity through ion modulated changes in pKa values.

In bacterial voltage gated sodium (Nav) channels, the passage of ions through the pore is controlled by a selectivity filter (SF) comprised of four glutamate residues. The mechanism of selectivity has been the subject of intense research, with suggested mechanisms based on steric effects, and ion triggered conformational change. Here we propose a novel mechanism based on ion-triggered shift in pKa values of SF glutamates. We study the NavMs channel for which the open channel structure is available. Our free energy calculations based on molecular dynamics simulations suggest that pKa values of the four glutamates are higher in solution of K+ ions, than in solution of Na+ ions. Since pKa values are close to the physiological pH, this results in predominant population of the fully deprotonated state of glutamates in Na+ solution, while protonated states are predominantly populated in K+ solution. Through molecular dynamics simulations we also calculate the conductances of the relevant protonation states. The deprotonated state is the most conductive, single protonated state is less conductive, and double protonated state has further reduced conductance. Thus, we propose that the selectivity is achieved through ion triggered shift in protonation state which favors more conductive states for Na+ ions and less conductive states for K+ ions. This mechanism would also suggest pH dependence of selectivity, which was experimentally observed in structurally similar NaChBas channels.

Double Pseudopolymeric [Au{S2CN(CH2)5}2]2[Ag2Cl4]·CH2Cl2 Complex: Preparation, Principles of Supramolecular Self-Assembly, Thermal Behavior, and Biological Activity against Mycolicibacterium smegmatis Strain

The double Au(III)–Ag(I) complex crystallizing as the solvated form of [Au{S2CN(CH2)5}2]2[Ag2Cl4]· CH2Cl2 (I) was obtained by the reaction of silver(I) N,N-pentamethylenedithiocarbamate with a solution of Na[AuCl4]/5.15 M NaCl. According to X-ray diffraction data (CIF file CCDC no. 2062810), the structural units of the compound are nonequivalent [Au{S2CN(CH2)5}2]+ cations (noncentrosymmetric A and centrosymmetric B and C in a ratio of 2 : 1 : 1), cyclic tetrachlorodiargentate(I) anions, [Ag2Cl4]2–, and solvating CH2Cl2 molecule. The latter is retained in the structure due to two nonequivalent C–H···Cl hydrogen bonds formed with the cyclic [Ag2Cl4]2– anion involving its terminal Cl(1) and bridging Cl(2) chlorine atoms. The supramolecular self-organization of I is based on a system of multiple Ag···S and Cl···S secondary interactions that сombine the ionic structural units of the complex into an intricate two-dimensional pseudopolymer layer. A study of the thermal behavior of I by simultaneous thermal analysis established the conditions for quantitative reduction of bound gold(III) and silver(I). The studied Au(III)–Ag(I) compound exhibits a high level of biological activity against the nonpathogenic M. smegmatis strain.

Nanoporosity and Isosteric Enthalpy of Adsorption of CH4, H2, and CO2 on Natural Chabazite and Exchanged

This paper describes the isosteric enthalpy through narrow pores at low levels of coverage through adsorption of CO2, CH4, and H2 on pores in natural chabazite exchanged with aqueous solutions of Na+, Mg2+, and Ca2+ salts at different concentrations, and with variable time and temperature of treatment. Experimental data of CO2, CH4, and H2 adsorption were treated by the Freundlich and Langmuir equations. Complementarily, the degree of interaction of these gases with these zeolites was evaluated by the evolution of isosteric enthalpy of adsorption. The exchange with Mg2+ and Na+ favors an increase in the adsorption capacity for CO2. while that of Ca2+ and Mg2+ favor adsorption through to H2 and CH4. These cations occupy sites in strategic positions S4 and S4’, which are located in the channels and nanocavities of these zeolites. The presence of Ca2+ and Mg2+ at S4 and S4′ sites causes increased adsorption into the nanocavities and on the external area of the ion-exchanged zeolites. Depending on the conditions of the exchange treatment, Ca2+ and Mg2+, and Na+ were found to be most favorable, well distributed, and accessible for CO2, CH4, and H2 adsorption.

Scaly lichen treatment

Sachs' received good results in fresh cases of psoriasis from intravenous administration of a 20% solution of Na salic., 10-20 kb each. sant. after 2-3 days, the total amount of Na salic administered reached 28.0.

Synthesis of silica coated on iron sand magnetic materials modified with 2- mercaptobenzimidazole through sol-gel

Synthesis of silica coated on iron sand magnetic materials modified with mercapto was carried out through a sol-gel method. This study aims to obtain adsorbent material that has magnetic properties. The purpose of this research are gift magnetic proprties of adsorbent. It was easy access to the separation of the adsorbent after the adsorption process in aqueous system. Modified silica surface with mercapto group provides spesific and selective for soft metals according to hard soft acid base (HSAB) principle. Solution of Na 2 SiO 3 as a silica precursor were coated on the surface of iron sand magnetic materials (MM) that has been activated by acid. Silica which have been coated on MM then modified with compound 2- mercaptobenzimidazole as a functional group of mercapto (-SH). The compound 2- mercaptobenzimidazole does not have a functional group of silanol (≡Si-OH) and siloxane (Si- O-Si) to bind to the functional group on silica surface. Therefore, chloropropyltrimethoxysilane (CPTMS) was added as a link between silica and 2-mercaptobenzimidazole. Chloropropyltrimethoxysilane (CPTMS) was reacted with 2-mercaptobenzimidazole as mixture I then mixed into silica which has coated MM as mixture II by sol-gel process. Material characterization was carried out by Fourier Transform Infrared (FTIR) spectrophotometer, X- ray diffractometer (XRD) and Vibrating Sample Magnetometer (VSM), and the stability of coated magnetite against acid. The characterization results showed that synthesized adsorbent of MM/SiO 2 /SH was successful. Coating of iron sand magnetic material with silica modified mercapto increases the stability of the acid and decreases the magnetic properties.

Strength Development Properties Of Sugar Cane Bagasse Ash Blended Geopolymer Concrete Containing Waste Steel Fibers

This research paper deals the two different mixture of GGBS/SCBA have been used for preparing the geopolymer alkali-activated concrete, by using NaOH (12 M solution), sodium silicate (12 M solution in Na+ and SiO2/Na2O molarity ratio of 0.3) and KOH (12 M solution) as activating solutions. Replacements of 10%, 20% and 30% of GGBS by SCBA were carried out for various mixes. It is observed that 20% replacement of GGBS showed better strength enhancement in the range 25-40 MPa at 3 days curing. However, the addition of waste steel fibers up to 1.5% by volume fraction (Vf) showed a reasonable improvements on the compressive strength and split tensile strength of geopolymer concrete. Further test results showed drastic improvement in flexural strength of geopolymer concrete for various mixes. The various comparative assessments were made for different geopolymer mixtures and the reinforcing effects of steel fibers were investigated in different concrete matrix.

Syntheses and Structures of Zinc(tmeda)bis(aryltellurolato) and its Facile Chalcogenospecific Ligand Exchange Reactivity

Anaerobic treatment of Zn(tmeda)Br2, where tmeda denotes N,N,N′,N′‐tetramethylethylenediamine, with a solution of Na(TeAr), sodium aryltellurolate, in ethanol in a 1:2 stoichiometry led to the formation of highly air sensitive Zn(tmeda)(TeAr)2 (1–3), while a 1:1 stoichiometry afforded Zn(tmeda)Br(TeAr) (4). Crystallography revealed all complexes to be monomeric with four coordinate central zinc atoms bound to tmeda and two TeAr, or a TeAr and a Br ligand. Upon mixing two symmetrically substituted Zn(tmeda)(TeAr)2 complexes in solution, 125Te NMR revealed a facile ligand exchange providing Zn(tmeda)(TeAr)(TeAr′). In addition, Zn(tmeda)(TeAr)(TeAr′) complexes form on mixing symmetric Zn(tmeda)(TeAr)2 complexes and (TeAr′)2. The lability of the zinc complexes was put to advantage in ligand‐substitution reactions wherein treatment of SnCl4 with Zn(tmeda)(TeAr)2 affords Sn(TeAr)4 in excellent yields without the concurrent formation of the redox product (TeAr)2. The apparent lability of the Zn–Te bond prevented the volatilization of 1–3 for their use as chemical vapor deposition precursors for the fabrication of ZnTe thin films. On heating, to volatize the complexes, the complexes decompose to cubic ZnTe and TeAr2 sublimes from the samples. Thermal gravimetric analysis indicates the loss of tmeda followed by the loss of TeAr2.

Thermodynamic and experimental study of corrosion behavior of vanadium-based alloy in liquid sodium-potassium coolant

A preliminary assessment of oxygen effect on vanadium solubility in Na–K melt eutectic composition has been carried out using mathematical framework of the subregular solution model and equations of coordination-cluster model. The effect of oxygen on the solubility of vanadium in the Na–K alloy can be considered as the result of short-range ordering in liquid metal solution. The negative deviations from the ideality for dilute oxygen solutions in Na–K solvent is one reason that explains the quantitative differences between Na and Na–K coolants, when we need to estimate the threshold oxygen concentration for the formation of ternary oxide NaVO2 on the surface of the solid vanadium in liquid sodium and in Na–K alloy. Isothermal capsule experiments qualitatively confirmed the results of calculations of vanadium solubility in Na0.32K0.68 alloy.

Investigation on chemical effects on GMZ bentonite used as buffer materials

GMZ bentonite has been selected as a buffer/backfill material for the design of Chinese HLW repository due to its suitable properties. Investigations have been conducted on this material to have a better understanding of its engineering behavior. In this paper, a review of the studies on the chemical effects in GMZ bentonite is presented. The adsorption of radionuclides Ni(II), Cr(III) and Eu(III) etc. on GMZ bentonite is investigated and the influences of external chemical agents are assessed. Some modifications on GMZ bentonite have been implemented to improve its adsorption properties. In the meantime, the influences of NaOH solutions with variations in concentration and pH values on hydraulic conductivity, mechanical behavior and mineralogy of GMZ bentonite are investigated with consideration of temperature. Effects of salt solutions are also assessed in different studies using solutions of Na+ and Ca2+ , which are the predominant cations in the groundwater of Beishan area. It is observed that both cations influence the buffering behavior of bentonite at a different degree. Further investigations should be done for better understanding the influences of coupling factors and time on the chemical behavior of material.

Salt preferences of honey bee water foragers.

The importance of dietary salt may explain why bees are often observed collecting brackish water, a habit that may expose them to harmful xenobiotics. However, the individual salt preferences of water-collecting bees were not known. We measured the proboscis extension reflex (PER) response of Apis mellifera water foragers to 0-10% w/w solutions of Na, Mg and K, ions that provide essential nutrients. We also tested phosphate, which can deter foraging. Bees exhibited significant preferences, with the most PER responses for 1.5-3% Na and 1.5% Mg. However, K and phosphate were largely aversive and elicited PER responses only for the lowest concentrations, suggesting a way to deter bees from visiting contaminated water. We then analyzed the salt content of water sources that bees collected in urban and semi-urban environments. Bees collected water with a wide range of salt concentrations, but most collected water sources had relatively low salt concentrations, with the exception of seawater and swimming pools, which had >0.6% Na. The high levels of PER responsiveness elicited by 1.5-3% Na may explain why bees are willing to collect such salty water. Interestingly, bees exhibited high individual variation in salt preferences: individual identity accounted for 32% of variation in PER responses. Salt specialization may therefore occur in water foragers.

Pollen and lithological data from the Bukovynka Cave deposits as recorders of the Late Pleistocene and Holocene climatic change in the eastern foothills of the Carpathian Mountains (Ukraine)

The study of clastic sediments of the BukovynkaCaveshows biotic and climatic changes during the Middle Pleniglacial (the Trapeznyi Chamber), Late Glacial and Holocene (the Sukhyi Chamber) in the south-eastern part of the Ukrainian Carpathians. The artesian BukovynkaCaveis located near the villageof Stal’nivtsi(the Chernivtsi region), in the PrutRiver basin. It is developed in the Miocene gypsum strata. The Quaternary clastic infilling of the cave, as well as mammal taphonomy has been previously studied in the Trapeznyi Chamber (Vremir et al., 2000; Ridush, 2004; Ridush et al., 2012), whereas palaeomagnetic research and its palaeoenvironmental implication has been provided for the Sukhyi Chamber (Bondar and Ridush, 2014). The results of pollen and grain-size studies of clastic deposits in both chambers, supported by mammal finds, are presented in this paper. In the Chernivtsi region, the pollen study has been previously performed (without 14 C-dating) on the Upper Pleistocene loess-paleosol section of Snyatyn and on the Onut site of the Holocene flood-plain deposits of the River Prut (Artyushenko et al., 1982). 39 samples from the cave sediments have been processed for grain-size analyses using the ‘pipette’ technique by Kachinsky (1965). In order to get pollen from clastic sediments, the following technique has been applied: heating with 10% HCl and 10% KOH, cold treatment with HF, disintegration in a solution of Na 4 P 2 O 7 and separation in heavy liquid (CdI 2 and KI) with a specific gravity 2.2. The abundance and good preservation of pollen show that the cave chambers turned periodically into sedimentation traps. Mammal bones are also mostly well preserved. Re-deposited pollen are abundant in the Trapeznyi Chamber but occur very rarely in the Suchyi Chamber. The present-day vegetation near the cave is a meadow-steppe surrounded by Carpinus-Quercus forest. The high proportion of Pinus sylvestris pollen in the surface soil samples (30-40%) does not correspond to the limited role that pine has in the modern vegetation. On the basis of this fact, pine pollen in the cave deposits are also regarded as over-represented because of its ability to travel farther on the wind than other pollen and its better preservation in rocks.

Sorption Characteristics of Cs on Weathered Biotite

To investigate the effect of the weathering process of biotite on Cs sorption, sorption experiment of Cs with solution was carried out on the biotite reacted at different reaction times at pH 2 and 4, and 1 M solutions of Na, K, Ca, Mg, Rb, and Cs. Peak changes were observed for some samples by XRD, indicating that new mineral phase formed by biotite weathering. Among several factors, cations in solutions have the most significant influence on the mineralogical changes. The samples reacted with Na showed the most outstanding change with increasing peak width and appearance of peak and peak. This new peaks indicate the formation of hydrobiotite and vermiculite. The new peaks had stronger peak intensity for the sample reacted at pH 4 than that at pH 2, probably due to the fast dissolution of small particles and edges and resultant decrease in the formation of expandable layers. The biotite reacted at Mg solution showed small intensity at . Based on XRD results, the degree of biotite weathering was in the order of Na, Mg, and Ca. The samples reacted with K, Rb, Cs solutions did not show noticeable mineralogical changes caused by weathering. The amount of sorbed Cs on weathered biotite showed close relationship with the degree of weathering indicated by XRD. At both pH 2 and 4, the biotite reacted with Na solution showed the highest Cs sorption, and those with Mg and Ca solutions showed the next highest ones. The sorbed amounts of Cs on the bitote reacted with K, Rb, Cs solutions were relatively low. This indicates that at the Cs concentration () which we used for this experiment and which was much higher than the maximum Cs concentration sorbed on the frayed edge site, expandable layer plays more important role than frayed edge. In the cases of K, Rb, and Cs solutions, Cs sorption was decreased because K is the same cations as the one in the interlayer or the sorption of Rb and Cs on the frayed edge prevents the formation of expandable layers.

Mechanical and durability properties of alkali-activated mortar based on sugarcane bagasse ash and blast furnace slag

Sugarcane bagasse is an agricultural waste which can be transformed, for cementing purposes, into an interesting material by combustion. Specifically, the ash (SBA) obtained by auto-combustion was used for preparing alkali-activated cements by blending blast furnace slag (BFS). SBA had a large amount of quartz; however, it reacted in high alkaline medium. Mixtures of BFS/SBA have been used for preparing alkali-activated mortars, by using NaOH (8M solution), sodium silicate (8M solution in Na+ and SiO2/Na2O molar ratio of 0.5) and KOH (8M solution) as activating solutions. Replacements of 25%, 33% and 50% of BFS by SBA were carried out and compressive strengths in the range 16–51MPa were obtained after 90 curing days. Microstructural studies demonstrated that the hydration products formed in the activation of BFS are not significantly affected by the presence of SBA in the mixture. The durability of alkali-activated mortars was compared to ordinary Portland cement (OPC) mortar in the following media: hydrochloric acid, acetic acid, ammonium chloride, sodium sulphate and magnesium sulphate. The behaviour of alkali-activated mortars with BFS and BFS/SBA was better than that found for plain OPC mortars, especially in ammonium chloride, acetic acid and sodium sulphate media. After 200 days of testing in ammonium chloride solution, the compressive strength loss for Portland cement mortar was about 83.3%. For the same test conditions, alkali-activated mortars presented a maximum reduction of 48.4%. The presence of SBA in alkali-activated BFS mortars did not produce any serious problems in durability. As a general conclusion, sugarcane bagasse ash (SBA) obtained by auto-combustion showed good cementing properties as a mineral precursor blended with blast furnace slag (BFS) in alkali-activated systems.

Determination of the Concentration of K<sup>+1</sup>, Na<sup>+1</sup> and Fe<sup>+2</sup> in Achane and Shay River a Case of Tepi Town

Physical environments such as rivers can be affected by the massive movement of chemicals from different human activities through run off system. Therefore the metals concentration can be fluctuated and can exceed level of tolerance and even become toxic. The objective of the work is to determine the concentration of metal ions. Water samples were obtained from two sites located around Teppi town namely Achane River and Shay River. From each river six replicate samples were obtained. The acidified plastic bottles were used for sample collection to avoid fluctuation in acidity because of different environmental factors. The standard solution used for calibration purpose is prepared by mixing the standard solution of Na+1 and K+1 metal ion. After standards are aspirated the concentration of potassium and sodium metal ions has been determined in unknown using flame photometry and Fe+2 determined by using Uv-visible spectroscopy. The concentration determined is in the range of 0ppm-10ppm. Hence the mean concentration of potassium is 2ppm and 1.33ppm in Achane and Shay River respectively. Concentration of sodium is 2.895ppm and 6.9ppm in Achane and Shay River respectively. Iron is determined to be 1.1ppm and 1.6ppm in Achane and Shay River respectively. The concentration of sodium and iron in Achane River is less than that of Shay River and potassium is higher slightly in Achane than Shay and finally the concentration of sodium in both rivers is greater than that of potassium and iron ion. No significant influence can be stated on health because of such detection; since it can be tolerated and of course improvement is needed.

Transformations of [Au(CN)2]− at the contact with activated carbon surface

We have studied the processes occurring when alkaline aqueous solution of Na[Au(CN)2] is brought in contact with activated carbon surface. It has been shown that the adsorption of the gold cyanide complex occurs via several independent routes, one of them being accompanied with the partial breakdown of the inner sphere of the compound and free cyanide ions release into the solution. The latter process decreases the gold recovery by aqueous NaOH during the high-temperature (150°C) desorption. A prolonged storage of the adsorbent saturated with [Au(CN)2]− in air produces a similar result. The reasons of the observed phenomena have been discussed.

ChemInform Abstract: First Incorporation of the Tetrahedral [Sn4]4‐ Cluster into a Discrete Solvate Na4[Sn4]·(NH3)13 from Solutions of Na4Sn4 in Liquid Ammonia.

AbstractNa4[Sn4]·13NH3 is obtained from deep red suspensions of Na4Sn4, Cu‐Mst, and 18‐crown‐6 in liquid NH3 (‐70 °C, 19 weeks, 25% yield).

Interactions between cations and water molecule bridges in soil organic matter

Nutrient release, soil wettability, water binding, and matrix rigidity of soil organic matter (SOM) can be affected by cross-links between segments of SOM, cations, and water molecule bridges (WaMB). Not all cation effects on SOM can be explained with the currently accepted idea that multivalent cations cross-link organic matter segments via direct cation bridges (CaB). The objective was to understand these interactions and their effect on SOM matrix rigidity and wettability. We modified cation composition of two peats and an organic surface layer (OSL) using cation exchange resin to remove cations and solutions of Na+, Ca2+, or Al3+ to enrich samples with cations. SOM matrix rigidity was determined at 4 and >8 weeks after treatment via the WaMB transition temperature T*, using differential scanning calorimetry. Wettability was measured via sessile drop contact angle (CA). The effect of cation removal on T* depended on cation exchange capacity and initial cation content. Cation addition to OSL increased T*. This effect increased with increasing cation loading and valency, and T* correlated with CA. Classical cross-linking can neither explain the higher heterogeneous matrix of Ca-treated than Al-treated samples nor the aging-induced convergence of T* for different cations and concentrations. The latter is likely due to interaction between CaB and WaMB in SOM. Associations of CaB and WaMB evolve slowly and form a supramolecular network in SOM. Those dynamic associations can fix molecular arrangements inducing water repellency and increase kinetic barriers for the release and uptake of water and nutrients from aged soil.

Effect of sodium silicate on the solubility of zinc oxide of the Na2O–ZnO–H2O equilibrium system

Abstract There is a competitive reaction of zinc and silica in the alkali leaching process of zinc oxide ore, leading to low zinc leaching rate. To increase leaching rate of zinc, the effect of sodium silicate on the solubility of zinc oxide of the Na 2 O–ZnO–SiO 2 –H 2 O equilibrium system is studied by adding Na 2 SiO 3 and ZnO to NaOH solution. Results show that zinc oxide equilibrium concentration increases with temperature from 25 to 75 °C at the same molar ratio of Na 2 O to SiO 2 . The equilibrium concentration of zinc oxide initially increases and then declines with the increasing concentration of Na 2 O. This leads to the maximum ZnO concentration, which increases with temperature but decreases with the increasing dosage of sodium silicate. The precipitate of disodium zinc silicate (Na 2 (ZnSiO 4 )) generates due to the reaction of silicate SiO 3 2 − and Zn(OH) 4 2 − in the solution of Na 2 O–ZnO–H 2 O equilibrium system. High zinc leaching rate can be obtained when the Na 2 O concentration is lower than the values indicated by the “peak” points at higher molar ratios of Na 2 O to SiO 2 and temperatures.

Denaturation of proteins by SDS and tetraalkylammonium dodecyl sulfates.

This article describes the use of capillary electrophoresis (CE) to examine the influence of different cations (C(+); C(+) = Na(+) and tetra-n-alkylammonium, NR(4)(+), where R = Me, Et, Pr, and Bu) on the rates of denaturation of bovine carbonic anhydrase II (BCA) in the presence of anionic surfactant dodecylsulfate (DS(-)). An analysis of the denaturation of BCA in solutions of Na(+)DS(-) and NR(4)(+)DS(-) (in Tris-Gly buffer) indicated that the rates of formation of complexes of denatured BCA with DS(-) (BCA(D)-DS(-)(n,sat)) are indistinguishable and independent of the cation below the critical micellar concentration (cmc) and independent of the total concentration of DS(-) above the cmc. At concentrations of C(+)DS(-) above the cmc, BCA denatured at rates that depended on the cation; the rates decreased by a factor >10(4) in the order of Na(+) ≈ NMe(4)(+) > NEt(4)(+) > NPr(4)(+) > NBu(4)(+), which is the same order as the values of the cmc (which decrease from 4.0 mM for Na(+)DS(-) to 0.9 mM for NBu(4)(+)DS(-) in Tris-Gly buffer). The relationship between the cmc values and the rates of formation of BCA(D)-DS(-)(n,sat()) suggested that the kinetics of denaturation of BCA involve the association of this protein with monomeric DS(-) rather than with micelles of (C(+)DS(-))(n). A less-detailed survey of seven other proteins (α-lactalbumin, β-lactoglobulin A, β-lactoglobulin B, carboxypeptidase B, creatine phosphokinase, myoglobin, and ubiquitin) showed that the difference between Na(+)DS(-) and NR(4)(+)DS(-) observed with BCA was not general. Instead, the influence of NR(4)(+) on the association of DS(-) with these proteins depended on the protein. The selection of the cation contributed to the properties (including the composition, electrophoretic mobility, and partitioning behavior in aqueous two-phase systems) of aggregates of denatured protein and DS(-). These results suggest that the variation in the behavior of NR(4)(+)DS(-) with changes in R may be exploited in methods used to analyze and separate mixtures of proteins.