sodium-perchlorate and sodium-sulfate

The hydrogen bond structure of water was examined by comparing the temperature dependent OH-stretching bands of water and aqueous NaClO

Topics: Hydrogen Bonding; Perchlorates; Potassium Compounds; Sodium Compounds; Sulfates; Temperature; Water

Lipid membranes are a key component of contemporary living systems and are thought to have been essential to the origin of life. Most research on membranes has focused on situations restricted to ambient physiological or benchtop conditions. However, the influence of more extreme conditions, such as the deep subsurface on Earth or extraterrestrial environments are less well understood. The deep subsurface environments of Mars, for instance, may harbor high concentrations of chaotropic salts in brines, yet we know little about how these conditions would influence the habitability of such environments for cellular life. Here, we investigated the combined effects of high concentrations of salts, including sodium and magnesium perchlorate and sulfate, and high hydrostatic pressure on the stability and structure of model biomembranes of varying complexity. To this end, a variety of biophysical techniques have been applied, which include calorimetry, fluorescence spectroscopies, small-angle X-ray scattering, dynamic light scattering, and microscopy techniques. We show that the structure and phase behavior of lipid membranes is sensitively dictated by the nature of the salt, in particular its anion and its concentration. We demonstrate that, with the exception of magnesium perchlorate, which can also induce cubic lipid arrangements, long-chain saturated lipid bilayer structures can still persist at high salt concentrations across a range of pressures. The lateral organization of complex heterogeneous raft-like membranes is affected by all salts. For simple, in particular bacterial membrane-type bilayer systems with unsaturated chains, vesicular structures are still stable at Martian brine conditions, also up to the kbar pressure range, demonstrating the potential compatibility of environments containing such ionic and pressure extremes to lipid-encapsulated life.

Topics: Atmospheric Pressure; Extraterrestrial Environment; Magnesium Compounds; Magnesium Sulfate; Mars; Molecular Conformation; Perchlorates; Phospholipids; Salts; Sodium Compounds; Spectrometry, Fluorescence; Structure-Activity Relationship; Sulfates; Thermodynamics

Topics: Dextrans; Hydrogen Bonding; Hydrophobic and Hydrophilic Interactions; Perchlorates; Polyethylene Glycols; Proteins; Sodium Chloride; Sodium Compounds; Solvents; Static Electricity; Sulfates; Water

Using small-angle X-ray scattering (SAXS), we obtained direct experimental evidence on the structure of hydrated polyatomic anions, with hydration effects starkly different from those of cations (J. Chem. Phys., 2011, 134, 064513). We propose that the size and charge density of the naked ions do not sufficiently account for the differences in the SAXS curves. For cations, the ion-ion contribution gives a prominent first-order diffraction peak, whereas for anions, the low-Q enhancement in the SAXS curves indicates density inhomogeneities as a result of ion-water interactions.

Topics: Ions; Perchlorates; Phosphates; Scattering, Small Angle; Sodium Compounds; Solutions; Sulfates; Water; X-Ray Diffraction

Partitioning of a homologous series of dinitrophenylted (DNP-) amino acids with aliphatic side chains was examined in aqueous polyethylene glycol (PEG)-8000-sodium sulfate two-phase systems (ATPS) with the additives NaSCN, NaClO4, and NaH2PO4 at concentrations varied from 0.025M up to 0.54M. The differences between the relative hydrophobicities and electrostatic properties of the two phases in all ATPS were estimated. Partitioning of adenine, adenosine mono-, di- and tri-phosphates was also examined in all ATPSs, including those with NaCl additive. Partition coefficients for these compounds and for nonionic organic compounds previously reported [L.A. Ferreira, P. Parpot, J.A. Teixeira, L.M. Mikheeva, B.Y. Zaslavsky, J. Chromatogr. A 1220 (2012) 14.] were analyzed in terms of linear solvent regression relationship. The results obtained suggest that the effects of the salts additives are related to their influence on the water structure.

Topics: Adenine Nucleotides; Amino Acids; Hydrophobic and Hydrophilic Interactions; Perchlorates; Phosphates; Polyethylene Glycols; Sodium Chloride; Sodium Compounds; Static Electricity; Sulfates; Thiocyanates; Water

The excess chemical potential of 1-propanol (1P), muE1P, was evaluated in ternary 1P-Na-salt(S)-H2O at 25 degrees C. The counter anions of the Na-salts studied are SO42-, F-, Cl-, I-, and ClO4-. The effect of the anion on muE1P follows the Hofmeister ranking, in that the more kosmotropic ions make the muE1P value more positive. We then evaluate the effect of the Na-salt (S) on muE1P, the 1P-S interaction in terms of excess chemical potential, at a semi-infinite dilution. The results indicate that the 1P-S interaction in terms of excess chemical potential is unfavorable (repulsive) for all of the ions studied. The degree of repulsive interaction decreases in the order of the Hofmeister ranking from the kosmotropic to the chaotropic end. Namely, salting-out samples make the excess part of the chemical potential of 1P more unfavorable, while the salting-in counterparts make it less unfavorable. From earlier calorimetric studies on the same ternary systems, the enthalpic 1P-S interaction function, HE 1P-S , was calculated. Hence, the entropy analogue, S1P-S , was also obtained, and a detailed thermodynamic signature of 1P-S interactions became available. This revealed that both HE 1P-S and SE 1P-S decrease from the kosmotropic ion to the middle of the ranking (Cl-), whereupon they turn to increase toward the chaotropic end. Hence, the build up of unfavorable 1P-S interactions in Hofmeister salts (signified by muE1P) relies on a pronounced enthalpy-entropy compensation, which must be accounted for in attempts to understand the molecular mechanisms underpinning Hofmeister effects.

Topics: 1-Propanol; Anions; Calorimetry; Models, Chemical; Perchlorates; Salts; Sodium Chloride; Sodium Compounds; Sodium Fluoride; Sodium Iodide; Sulfates; Thermodynamics; Water

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.

Topics: Anesthetics, Local; Benzocaine; Drug Stability; Hydrolysis; Models, Chemical; Perchlorates; Salts; Sodium Compounds; Sodium Hydroxide; Solubility; Sulfates; Tetraethylammonium

The effects of salts on the rate constants of inactivation by heat of yeast alcohol dehydrogenase (YADH) at 60.0 degrees C were measured. Different effects were observed at low and high salt concentrations. At high concentrations, some salts had stabilizing effects, while others were destabilizing. The effects of salts in the high concentration range examined can be described as follows: (decreased thermal stability) NaClO(4) < NaI = (C(2)H(5))(4)NBr < NH(4)Br < NaBr = KBr = CsBr = (no addition) < (CH(3))(4)NBr < KCl < KF < Na(2)SO(4) (increased thermal stability). The decreasing effect of NaClO(4) on YADH controlled the thermal stability of the enzyme absolutely and was not compensated by the addition of Na(2)SO(4), a salt which stabilized the enzyme. However, Na(2)SO(4) compensation did occur in response to the decrease in thermal stability caused by (C(2)H(5))(4)NBr. The rate constants of inactivation by heat (k (in)) of the enzyme were measured at various temperatures. Effective values of the thermodynamic activation parameters of thermal inactivation, activation of free energy (DeltaG (double dagger)), activation enthalpy (DeltaH (double dagger)), and activation entropy (DeltaS (double dagger)), were determined. The thermal stability of YADH in 0.8 M Na(2)SO(4) increased more than that of pyruvate kinase from Bacillus stearothermophilus, a moderate thermophile. The changes in the values of DeltaH (double dagger) and DeltaS (double dagger) were great and showed a general compensatory tendency, with the exception of in the case of NaClO(4). The temperature for the general compensation effect (T (c)) was approximately 123 degrees C. With Na(2)SO(4), the thermal stability of YADH at a temperature below T (c) was greater than that in the absence of salt due to the higher values of DeltaH (double dagger) and DeltaS (double dagger), respectively, and thus was an example of low-temperature enzymatic stabilization. With (C(2)H(5))(4)NBr, the thermal stability of YADH at a temperature below T (c) was lower than that in the absence of salt due to the lower values of DeltaH (double dagger) and DeltaS (double dagger), respectively, and thus was an example of low-temperature enzymatic destabilization. But with NaClO(4), the changes in the values of DeltaH (double dagger) and DeltaS (double dagger) were small and the thermal stability of YADH was thus an example of high-temperature enzymatic destabilization.

Topics: Alcohol Dehydrogenase; Cations, Monovalent; Entropy; Enzyme Stability; Fluorides; Hot Temperature; Kinetics; Perchlorates; Potassium Compounds; Saccharomyces cerevisiae; Sodium Compounds; Sodium Iodide; Sulfates; Thermodynamics