201
|
Guo F, Friedman JM. Charge density-dependent modifications of hydration shell waters by Hofmeister ions. J Am Chem Soc 2009; 131:11010-8. [PMID: 19603752 PMCID: PMC2745343 DOI: 10.1021/ja902240j] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Gadolinium (Gd(3+)) vibronic sideband luminescence spectroscopy (GVSBLS) is used to probe, as a function of added Hofmeister series salts, changes in the OH stretching frequency derived from first-shell waters of aqueous Gd(3+) and of Gd(3+) coordinated to three different types of molecules: (i) a chelate (EDTA), (ii) structured peptides (mSE3/SE2) of the lanthanide-binding tags (LBTs) family with a single high-affinity binding site, and (iii) a calcium-binding protein (calmodulin) with four binding sites. The vibronic sideband (VSB) corresponding to the OH stretching mode of waters coordinated to Gd(3+), whose frequency is inversely correlated with the strength of the hydrogen bonding to neighboring waters, exhibits an increase in frequency when Gd(3+) becomes coordinated to either EDTA, calmodulin, or mSE3 peptide. In all of these cases, the addition of cation chloride or acetate salts to the solution increases the frequency of the vibronic band originating from the OH stretching mode of the coordinated waters in a cation- and concentration-dependent fashion. The cation dependence of the frequency increase scales with charge density of the cations, giving rise to an ordering consistent with the Hofmeister ordering. On the other hand, water Raman spectroscopy shows no significant change upon addition of these salts. Additionally, it is shown that the cation effect is modulated by the specific anion used. The results indicate a mechanism of action for Hofmeister series ions in which hydrogen bonding among hydration shell waters is modulated by several factors. High charge density cations sequester waters in a configuration that precludes strong hydrogen bonding to neighboring waters. Under such conditions, anion effects emerge as anions compete for hydrogen-bonding sites with the remaining free waters on the surface of the hydration shell. The magnitude of the anion effect is both cation and Gd(3+)-binding site specific.
Collapse
Affiliation(s)
- Feng Guo
- Department of Biophysics and Physiology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, New York, U.S.A. 10461
| | - Joel M. Friedman
- Department of Biophysics and Physiology, Albert Einstein College of Medicine, 1300 Morris Park Ave., Bronx, New York, U.S.A. 10461
| |
Collapse
|
202
|
Van Itallie CM, Holmes J, Bridges A, Anderson JM. Claudin-2-dependent changes in noncharged solute flux are mediated by the extracellular domains and require attachment to the PDZ-scaffold. Ann N Y Acad Sci 2009; 1165:82-7. [PMID: 19538292 DOI: 10.1111/j.1749-6632.2009.04052.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Paracellular transport through the tight junction shows selectivity for both ionic charge and solute size. It is known that charged residues on the extracellular loops of claudins control charge selectivity. It is also known that inducible expression of claudin-2, but not claudin-4, will selectively increase the permeability for polyethylene glycol (PEG) molecules which are <0.4 A in radius, but it is not known whether permeability is controlled by the same regions of claudins which control charge selectivity. Using inducible expression of chimeras of claudin-2 and claudin-4 in monolayers of MDCK II cells we show that the extracellular loops alone are responsible for controlling the permeability for noncharged PEGs as well as for charge selectivity. Further, the cytoplasmic C-terminal PDZ-binding motif is required for wild-type claudin-2 to control permeability, suggesting a requirement for attachment to the PDZ scaffold in order to form pores. These observations support a model where the loops form pores controlling permeability for both charged and noncharged solutes which are smaller than 0.4 A. They leave unanswered why both claudin-2 and -4 can influence electrical properties while only -2 can selectively increase permeability for small PEGs.
Collapse
|
203
|
Banasiak LJ, Schäfer AI. Removal of boron, fluoride and nitrate by electrodialysis in the presence of organic matter. J Memb Sci 2009. [DOI: 10.1016/j.memsci.2009.02.020] [Citation(s) in RCA: 137] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
204
|
López-Muñoz MJ, Sotto A, Arsuaga JM, Van der Bruggen B. Influence of membrane, solute and solution properties on the retention of phenolic compounds in aqueous solution by nanofiltration membranes. Sep Purif Technol 2009. [DOI: 10.1016/j.seppur.2008.11.001] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
|
205
|
Ben Fredj A, Ben Lakhdar Z, Ruiz-López M. Six-coordination in Chlorophylls: The fundamental role of dispersion energy. Chem Phys Lett 2009. [DOI: 10.1016/j.cplett.2009.03.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
206
|
Zhou Y, Yu S, Gao C, Feng X. Surface modification of thin film composite polyamide membranes by electrostatic self deposition of polycations for improved fouling resistance. Sep Purif Technol 2009. [DOI: 10.1016/j.seppur.2008.12.021] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
207
|
|
208
|
Fornero JJ, Rosenbaum M, Cotta MA, Angenent LT. Microbial fuel cell performance with a pressurized cathode chamber. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2008; 42:8578-8584. [PMID: 19068851 DOI: 10.1021/es8015292] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Microbial fuel cell (MFC) power densities are often constrained by the oxygen reduction reaction rate on the cathode electrode. One important factor for this is the normally low solubility of oxygen in the aqueous cathode solution, which creates mass transport limitation and hinders oxygen reduction at the electrocatalyst (platinum, Pt). Here, we increased the air pressure in the cathode chamber to increase the solubility and consequently the availability of oxygen, which is a function of the partial pressure. Under stable anode and cathode conditions, an MFC was tested with an anion-exchange membrane (AEM) and a cation-exchange membrane (CEM) at atmospheric pressure, +17.24 kPa (2.5 psig), and +34.48 kPa (5.0 psig) overpressure of air. The cell potential at an external resistance of 100 omega increased from 0.423 to 0.553 V by increasing the cathode pressure from atmospheric pressure to 17.24 kPa for an MFC with AEM, and this resulted in a 70% increase in the power density (4.29 vs 7.29 W/m3). In addition, the MFC produced 66-108% more power with AEM in comparison to CEM under the same operating conditions. We discussed the mechanisms that explain this. Results from this study demonstrate that higher MFC power densities can be realized by increasing the cathode air pressure if the membrane oxygen diffusion to the anode can be controlled.
Collapse
Affiliation(s)
- Jeffrey J Fornero
- Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, One Brookings Drive, CB 1180, St. Louis, Missouri 63130, USA
| | | | | | | |
Collapse
|
209
|
Petersen PB, Saykally RJ. Is the liquid water surface basic or acidic? Macroscopic vs. molecular-scale investigations. Chem Phys Lett 2008. [DOI: 10.1016/j.cplett.2008.04.010] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
210
|
|
211
|
Crystallographic study of hydration of an internal cavity in engineered proteins with buried polar or ionizable groups. Biophys J 2008; 94:3208-16. [PMID: 18178652 DOI: 10.1529/biophysj.107.122473] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although internal water molecules are essential for the structure and function of many proteins, the structural and physical factors that govern internal hydration are poorly understood. We have examined the molecular determinants of internal hydration systematically, by solving the crystal structures of variants of staphylococcal nuclease with Gln-66, Asn-66, and Tyr-66 at cryo (100 K) and room (298 K) temperatures, and comparing them with existing cryo and room temperature structures of variants with Glu-66, Asp-66, Lys-66, Glu-92 or Lys-92 obtained under conditions of pH where the internal ionizable groups are in the neutral state. At cryogenic temperatures the polar moieties of all these internal side chains are hydrated except in the cases of Lys-66 and Lys-92. At room temperature the internal water molecules were observed only in variants with Glu-66 and Tyr-66; water molecules in the other variants are probably present but they are disordered and therefore undetectable crystallographically. Each internal water molecule establishes between 3 and 5 hydrogen bonds with the protein or with other internal water molecules. The strength of interactions between internal polar side chains and water molecules seems to decrease from carboxylic acids to amides to amines. Low temperature, low cavity volume, and the presence of oxygen atoms in the cavity increase the positional stability of internal water molecules. This set of structures and the physical insight they contribute into internal hydration will be useful for the development and benchmarking of computational methods for artificial hydration of pockets, cavities, and active sites in proteins.
Collapse
|
212
|
Xu M, Larentzos JP, Roshdy M, Criscenti LJ, Allen HC. Aqueous divalent metal–nitrate interactions: hydration versus ion pairing. Phys Chem Chem Phys 2008; 10:4793-801. [DOI: 10.1039/b807090n] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
213
|
Müller E, Faude A. Investigation of salt properties with electro-acoustic measurements and their effect on dynamic binding capacity in hydrophobic interaction chromatography. J Chromatogr A 2008; 1177:215-25. [DOI: 10.1016/j.chroma.2007.11.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Revised: 11/02/2007] [Accepted: 11/06/2007] [Indexed: 10/22/2022]
|
214
|
Rossi S, Lo Nostro P, Lagi M, Ninham BW, Baglioni P. Specific Anion Effects on the Optical Rotation of α-Amino Acids. J Phys Chem B 2007; 111:10510-9. [PMID: 17691834 DOI: 10.1021/jp0721806] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Changes in optical rotation of some alpha-amino acids are induced by electrolytes. Such effects on l- and d-enantiomers of a range of amino acids are explored for sodium salts with varying anion. The amino acids studied were alanine, aspartic acid, glutamic acid, glutamine, proline, threonine, and tryptophan. The anion's polarizability in solution accounts for the change in [alpha] only for the halides. Self-association of amino acids in solution and pH changes due to the presence of the electrolytes do not account for the observed variations in optical activity. Specific interactions of anions with the chiral amino acids (Hofmeister effects) and salt-induced perturbations of the amino acid hydration shell appear to be responsible for the effects, and conformational changes in the chiral solutes due to the presence of ionic species are discussed.
Collapse
Affiliation(s)
- Simona Rossi
- Department of Chemistry and CSGI, University of Florence, via della Lastruccia 3, 50019 Sesto Fiorentino (Firenze), Italy
| | | | | | | | | |
Collapse
|
215
|
Collins KD, Neilson GW, Enderby JE. Ions in water: Characterizing the forces that control chemical processes and biological structure. Biophys Chem 2007; 128:95-104. [PMID: 17418479 DOI: 10.1016/j.bpc.2007.03.009] [Citation(s) in RCA: 433] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 03/09/2007] [Accepted: 03/10/2007] [Indexed: 11/29/2022]
Abstract
The continuum electrostatics model of Debye and Hückel [P. Debye and E. Hückel, On the theory of electrolytes. I. Freezing point depression and related phenomena., Phys. Z. 24 (1923) 185-206.] and its successors utilize a macroscopic dielectric constant and assume that all interactions involving ions are strictly electrostatic, implying that simple ions in water generate electric fields strong enough to orient water dipoles over long distances. However, solution neutron and X-ray diffraction indicate that even di- and tri-valent ions do not significantly alter the density or orientation of water more than two water molecules (5 A) away. Therefore the long range electric fields (generated by simple ions) which can be detected by various resonance techniques such as fluorescence resonance energy transfer over distances of 30 A (about 11 water diameters) or more must be weak relative to the strength of water-water interactions. Two different techniques indicate that the interaction of water with anions is by an approximately linear hydrogen bond, suggesting that the dominant forces on ions in water are short range forces of a chemical nature.
Collapse
Affiliation(s)
- Kim D Collins
- Center of Marine Biotechnology and Medical Biotechnology Center, University of Maryland Biotechnology Institute, Baltimore, MD 21201, USA.
| | | | | |
Collapse
|
216
|
Fujita K, MacFarlane DR, Forsyth M, Yoshizawa-Fujita M, Murata K, Nakamura N, Ohno H. Solubility and stability of cytochrome c in hydrated ionic liquids: effect of oxo acid residues and kosmotropicity. Biomacromolecules 2007; 8:2080-6. [PMID: 17580947 DOI: 10.1021/bm070041o] [Citation(s) in RCA: 297] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Hydrated ionic liquids (ILs) were prepared by adding appropriate amounts of water to hydrophilic ILs. Some hydrated ILs show excellent solubilizing ability for proteins, keeping the basic properties of ILs. The solubility of cytochrome c (cyt c) depended on the structure of the component ions. When component anions have oxo acid residues, the resulting hydrated ILs solubilize cyt c quite well. In such hydrated ILs, the structure and activity of cyt c is influenced by the kosmotropicity of the component ions. We synthesized ILs from various ions having different kosmotropicity, including dihydrogen phosphate (dhp), dibutylphosphate, acetate, lactate, and methanesulfonate as anions. The activity of the dissolved cyt c depends on the permutations of kosmotropicity of the component ions. cyt c shows no structural change and retains its activity when dissolved in the hydrated choline dhp, which is an excellent combination of chaotropic cation and kosmotropic anion. Furthermore, cyt c dissolved in the hydrated choline dhp remained in a native state and was active after 18 months of storage at room temperature.
Collapse
Affiliation(s)
- Kyoko Fujita
- Department of Biotechnology, Tokyo University of Agriculture and Technology, Koganei, Tokyo, Japan
| | | | | | | | | | | | | |
Collapse
|
217
|
|
218
|
Chirila TV, Hill AJ, Richens DT. Effect of Redundant Chain Packing on the Uptake of Calcium Phosphate in Poly(2-Hydroxyethyl Methacrylate) Hydrogels. Aust J Chem 2007. [DOI: 10.1071/ch07111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A method is described that allows reduction of the amount of calcium phosphate phases deposited spontaneously inside poly(2-hydroxyethyl methacrylate) (PHEMA), a hydrogel of biomedical importance. PHEMA homo-interpenetrating polymer networks (homo-IPNs) were synthesized and then treated in a calcifying solution. A reduction of calcium uptake of 58 to 75% was measured by ICP emission spectroscopy in the IPNs as compared to the PHEMA homopolymer (the parent network). The effect was rationalized in terms of reduction of the free volume available for the penetration and transport of Ca2+ and phosphate ions as a result of redundant chain packing through formation of IPNs.
Collapse
|
219
|
Abstract
Regulation of transmembrane ion transport is a vital aspect of bioinorganic chemistry. To understand how this highly selective process occurs, how it can become impaired and how impairment may be treated, model compounds are useful tools. Several systems are presently being explored but one of the most widely applicable combines a rigid macrocycle, capable of size-based ion recognition, with membrane-spanning substituents that allow the target ions to traverse a phospholipid bilayer. The calixarene class of macrocycles is ideally suited to this task. This article sets out the biological background to transmembrane ion transport, the methods available to study the phenomenon, examples of model compounds, and proposes areas of further study.
Collapse
Affiliation(s)
- Khayzuran S J Iqbal
- School of Pharmacy and Biomolecular Sciences, University of Brighton, Cockcroft Building, Moulsecoomb, Brighton, UK BN2 4GJ
| | | |
Collapse
|
220
|
Sigel RKO, Pyle AM. Alternative Roles for Metal Ions in Enzyme Catalysis and the Implications for Ribozyme Chemistry. Chem Rev 2006; 107:97-113. [PMID: 17212472 DOI: 10.1021/cr0502605] [Citation(s) in RCA: 222] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Roland K O Sigel
- Institute of Inorganic Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
| | | |
Collapse
|
221
|
Lo Nostro P, Ninham BW, Milani S, Lo Nostro A, Pesavento G, Baglioni P. Hofmeister effects in supramolecular and biological systems. Biophys Chem 2006; 124:208-13. [PMID: 16678961 DOI: 10.1016/j.bpc.2006.04.004] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2005] [Revised: 04/14/2006] [Accepted: 04/14/2006] [Indexed: 11/19/2022]
Abstract
Specific ion effects, representative of near-universal Hofmeister phenomena, are illustrated in three different systems. These are the formation of supramolecular assemblies from cyclodextrins, the optical rotation of L-serine, and the growth rate of two kinds of microorganisms (Staphylococcus aureus and Pseudomonas aeruginosa). The strong specific ion effects can be correlated with the anion polarizabilities and related physico-chemical parameters. The results show the relevance of dispersion (non-electrostatic) forces in these phenomena.
Collapse
Affiliation(s)
- Pierandrea Lo Nostro
- Department of Chemistry and CSGI, University of Florence, 50019 Sesto Fiorentino (Firenze), Italy.
| | | | | | | | | | | |
Collapse
|
222
|
Nghiem LD, Schäfer AI, Elimelech M. Role of electrostatic interactions in the retention of pharmaceutically active contaminants by a loose nanofiltration membrane. J Memb Sci 2006. [DOI: 10.1016/j.memsci.2006.09.011] [Citation(s) in RCA: 168] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
223
|
Saxena A, Kumar A, Shahi VK. Preparation and characterization of N-methylene phosphonic and quaternized chitosan composite membranes for electrolyte separations. J Colloid Interface Sci 2006; 303:484-93. [PMID: 16949087 DOI: 10.1016/j.jcis.2006.07.061] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 07/24/2006] [Accepted: 07/24/2006] [Indexed: 11/24/2022]
Abstract
Chitosan was functionalized either by introducing a phosphonic acid group or by quaternization of existing primary ammonium groups in order to make it a water-soluble material. Functionalized chitosans and poly(vinyl alcohol) (PVA)-based nanoporous charged membranes were prepared in aqueous media and gelated in methanol at 10 degrees C to tailor their pore structure. These membranes were extensively characterized for their physicochemical, electrochemical, and permeation characteristics using FTIR, TGA, DSC, water content, ion-exchange capacity, ionic transport properties, and membrane permeability studies. N-Methylene phosphonic chitosan (NMPC)/PVA-based membranes exhibited mild cation selectivity and quaternized chitosan (QC)/PVA composite membranes had mild anion selectivity, while a blend of NMPC-QC/PVA membranes exhibited weak cation selectivity because of formation of zwitterionic structure. Viscosity measurements and interaction studies for individual and mixed solutions of NMPC and QC were carried out for the prediction of charge interactions between -PO3H2 and -N+(CH3)3 groups and effect on molecular weight due to functionalization. Elaborate electrochemical and permeation experiments were conducted in order to predict suitability of these membranes for the separation of mono- and bivalent electrolytes based on their hydrated ionic radius, and it was found that among all the synthesized membranes, PC/QC-30 had the highest relative permeability, which may extend its suitability for electrolyte separations. Observations were correlated with equivalent pore radius of the different membranes as estimated by membrane permeability measurements.
Collapse
Affiliation(s)
- Arunima Saxena
- Electro-Membrane Processes Division, Central Salt & Marine Chemicals Research Institute, Bhavnagar 364002, India
| | | | | |
Collapse
|
224
|
Roche CJ, Guo F, Friedman JM. Molecular level probing of preferential hydration and its modulation by osmolytes through the use of pyranine complexed to hemoglobin. J Biol Chem 2006; 281:38757-68. [PMID: 17057250 DOI: 10.1074/jbc.m608835200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Two spectroscopic probes are used to expose molecular level changes in hydration shell water interactions that directly relate to such issues as preferential hydration and protein stability. The major focus of the present study is on the use of pyranine (HPT) fluorescence to probe as a function of added osmolytes (PEG, urea, trehalose, and magnesium), the extent to which glycerol is preferentially excluded from the hydration shell of free HPT and HPT localized in the diphosphoglycerate (DPG) binding site of hemoglobin in both solution and in Sol-Gel matrices. The pyranine study is complemented by the use of vibronic side band luminescence from the gadolinium cation that directly exposes the changes in hydrogen bonding between first and second shell waters as a function of added osmolytes. Together the results form the basis for a water partitioning model that can account for both preferential hydration and water/osmolyte-mediated conformational changes in protein structure.
Collapse
Affiliation(s)
- Camille J Roche
- Department of Physiology and Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | | | | |
Collapse
|
225
|
Murgia S, Portesani F, Ninham BW, Monduzzi M. Interaction of Sodium Ions with Cationic Surfactant Interfaces. Chemistry 2006; 12:7889-98. [PMID: 16847988 DOI: 10.1002/chem.200600080] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The thermodynamically stable microemulsion and lamellar phases in the didodecyldimethylammonium bromide/water/n-decane ternary system were explored in the presence of NaBr to gain information on sodium ion-interface interactions. Experimental results, obtained by different NMR techniques, strongly suggest accumulation of sodium ions at the cationic interface. This apparently counterintuitive result is explained by invoking the dispersion potential experienced by the ions near the interface. A mechanism is proposed that can account for the dramatic shrinkage of the microemulsion phase region when an electrolyte is added.
Collapse
Affiliation(s)
- Sergio Murgia
- Dipartimento di Scienze Chimiche, Università di Cagliari - CSGI Cittadella Monserrato, S.S. 554 Bivio Sestu, 09042 Monserrato, Italy
| | | | | | | |
Collapse
|
226
|
Koga Y, Katayanagi H, Davies JV, Kato H, Nishikawa K, Westh P. The Effects of Chloride Salts of Some Cations on the Molecular Organization of H2O. Towards Understanding the Hofmeister Series. II. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2006. [DOI: 10.1246/bcsj.79.1347] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
|
227
|
Significance of hydrated radius and hydration shells on ionic permeability during nanofiltration in dead end and cross flow modes. Sep Purif Technol 2006. [DOI: 10.1016/j.seppur.2005.12.020] [Citation(s) in RCA: 440] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
228
|
Westh P, Kato H, Nishikawa K, Koga Y. Toward Understanding the Hofmeister Series. 3. Effects of Sodium Halides on the Molecular Organization of H2O As Probed by 1-Propanol. J Phys Chem A 2006; 110:2072-8. [PMID: 16451045 DOI: 10.1021/jp055036y] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We investigated the effects of NaF, NaCl, NaBr, and NaI on the molecular organization of H2O by a calorimetric methodology developed by us earlier. We use the third derivative quantities of G pertaining to 1-propanol (1P) in ternary 1P-a salt-H2O as a probe to elucidate the effects of a salt on H2O. We found that NaF and NaCl worked as hydration centers. The hydration numbers were 19 +/- 2 for NaF and 7.5 +/- 0.6 for NaCl. Furthermore, the bulk H2O away from the hydration shell was found unaffected by the presence of Na+, F-, and Cl-. For NaBr and NaI, in addition to the hydration to Na+, Br- and I- acted like a hydrophilic moiety such as urea. Namely, they formed a hydrogen bond to the existing H2O network and retarded the fluctuation nature of H2O. These findings were discussed with respect to the Hofmeister ranking. We suggested that more chaotropic anions Br- and I- are characterized as hydrophiles, whereas kosmotropes, F- and Cl-, are hydration centers.
Collapse
Affiliation(s)
- Peter Westh
- Department of Life Sciences and Chemistry, Roskilde University, Roskilde, DK-4000, Denmark
| | | | | | | |
Collapse
|
229
|
Lo Nostro P, Ninham BW, Milani S, Fratoni L, Baglioni P. Specific anion effects on the optical rotation of glucoseand serine. Biopolymers 2006; 81:136-48. [PMID: 16215991 DOI: 10.1002/bip.20389] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Optical activity is directly related to molecular conformation through the anisotropic polarizabilities of molecules and the refractive index of materials. L-amino acids and D-sugars are characteristic essential bioactive molecules. Since molecular recognition and enzyme activity are related to the conformation of substrates, the relevance of optical activity to biological processes is evident. Specific ion, or Hofmeister, effects that occur with electrolytes at moderately high concentrations modify the behavior of interfaces, molecular forces between membranes, of bulk solutions, of enzymes, and even of DNA. Such effects are universal. Here we report a study on the change in optical rotation induced by some sodium salts for the enantiomers of serine and glucose in water solution. The optical rotation is shown to depend on the kind of anion and on the salt concentration. To obtain further insights into the mechanism behind the phenomenon, Fourier transform infrared (FTIR) spectral studies of serine and glucose solutions in electrolytes were also carried out. The results suggest that it is the differences in interactions of anions at specific chemical sites of the solutes that are responsible for the effects. These forces depend strongly on anion polarizability in water. Such specific ion preferential interactions can affect conformation and internal field, and result in significant changes in optical rotation.
Collapse
Affiliation(s)
- Pierandrea Lo Nostro
- Department of Chemistry and CSGI, University of Florence, via della Lastruccia 3, 50019 Sesto Fiorentino (Firenze), Italy.
| | | | | | | | | |
Collapse
|
230
|
Prospective energy densities in the forisome, a new smart material. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2006. [DOI: 10.1016/j.msec.2005.06.055] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
231
|
Parsons MT, Koga Y. Hydration number of glycine in aqueous solution: An experimental estimate. J Chem Phys 2005; 123:234504. [PMID: 16392928 DOI: 10.1063/1.2138698] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
An experimental estimate of hydration number, N(H), of glycine in aqueous solution is given by using the calorimetric methodology developed by us earlier, which is briefly reviewed. We found NH to be 7+/-0.6 for glycine presumably in the zwitter ion form, 10+/-1 for sodium glycinate, and 5+/-0.4 for glycine hydrochloride. Both glycine and sodium glycinate seem to work purely as a hydration center without altering the nature of the bulk H2O away from the hydration shell. Glycine hydrochloride, in addition to the role of hydration center, seems also to act as a typical hydrophilic species such as polyols, urea, or polyethylene glycols. Hence, the effect of the latter on H2O is of a long range, like other hydrophilic species.
Collapse
Affiliation(s)
- Matthew T Parsons
- Department of Chemistry, The University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | | |
Collapse
|
232
|
Wahab A, Mahiuddin S, Hefter G, Kunz W, Minofar B, Jungwirth P. Ultrasonic Velocities, Densities, Viscosities, Electrical Conductivities, Raman Spectra, and Molecular Dynamics Simulations of Aqueous Solutions of Mg(OAc)2 and Mg(NO3)2: Hofmeister Effects and Ion Pair Formation. J Phys Chem B 2005; 109:24108-20. [PMID: 16375403 DOI: 10.1021/jp053344q] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The ultrasonic velocities, densities, viscosities, and electrical conductivities of aqueous solutions of magnesium nitrate and magnesium acetate have been measured from dilute to saturation concentrations at 0 < or = t/degrees C < or = 50. The temperature derivative of the isentropic compressibility, kappa(s), became zero at 2.28 and 2.90 mol kg(-1) for Mg(OAc)2 and Mg(NO3)2 solutions, respectively, at 25 degrees C. The total hydration numbers of the dissolved ions were estimated to be, respectively, 24.3 and 19.2 at these concentrations. Differences in kappa(s) for various M2+ salts, using the present and literature data, correlated with reported M2+-OH2 bond lengths and to a lesser extent with cationic charge densities (ionic radii). The influence of anions on kappa(s) appears to follow the Hofmeister series and also correlates approximately with the anionic charge density. Substantial differences between Mg(OAc)2(aq) and Mg(NO3)2(aq) occur with respect to their structural relaxation times (derived from compressibility and viscosity data) and their electrical conductivities. These differences were attributed to a much greater ion association in Mg(OAc)2 solutions. Raman spectra recorded at 28 degrees C confirmed the presence of various types of contact ion pairs including mono- and bidentate complexes in Mg(OAc)2(aq). In Mg(NO3)2(aq), only noncontact ion pairs appear to be formed even at high concentrations. The experimental results are supported by molecular dynamics simulations, which also reveal the much stronger tendency of OAc- compared to NO3- to associate with Mg2+ in aqueous solutions. The simulations also allow an evaluation of the ion-ion and ion-water radial distribution functions and cumulative sums and provide a molecular picture of ion hydration in Mg(OAc)2(aq) and Mg(NO3)2(aq) at varying concentrations.
Collapse
Affiliation(s)
- Abdul Wahab
- Material Science Division, Regional Research Laboratory, Jorhat--785 006, Assam, India
| | | | | | | | | | | |
Collapse
|
233
|
Broering JM, Bommarius AS. Evaluation of Hofmeister Effects on the Kinetic Stability of Proteins. J Phys Chem B 2005; 109:20612-9. [PMID: 16853668 DOI: 10.1021/jp053618+] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Dissolved salts are known to affect properties of proteins in solution including solubility and melting temperature, and the effects of dissolved salts can be ranked qualitatively by the Hofmeister series. We seek a quantitative model to predict the effects of salts in the Hofmeister series on the deactivation kinetics of enzymes. Such a model would allow for a better prediction of useful biocatalyst lifetimes or an improved estimation of protein-based pharmaceutical shelf life. Here we consider a number of salt properties that are proposed indicators of Hofmeister effects in the literature as a means for predicting salt effects on the deactivation of horse liver alcohol dehydrogenase (HL-ADH), alpha-chymotrypsin, and monomeric red fluorescent protein (mRFP). We find that surface tension increments are not accurate predictors of salt effects but find a common trend between observed deactivation constants and B-viscosity coefficients of the Jones-Dole equation, which are indicative of ion hydration. This trend suggests that deactivation constants (log k(d,obs)) vary linearly with chaotropic B-viscosity coefficients but are relatively unchanged in kosmotropic solutions. The invariance with kosmotropic B-viscosity coefficients suggests the existence of a minimum deactivation constant for proteins. Differential scanning calorimetry is used to measure protein melting temperatures and thermodynamic parameters, which are used to calculate the intrinsic irreversible deactivation constant. We find that either the protein unfolding rate or the rate of intrinsic irreversible deactivation can control the observed deactivation rates.
Collapse
Affiliation(s)
- James M Broering
- School of Chemical & Biomolecular Engineering, School of Chemistry and Biochemistry, Georgia Institute of Technology, 315 Ferst Drive, Atlanta, GA 30332-0363, USA
| | | |
Collapse
|
234
|
Collins KD. Ion hydration: Implications for cellular function, polyelectrolytes, and protein crystallization. Biophys Chem 2005; 119:271-81. [PMID: 16213082 DOI: 10.1016/j.bpc.2005.08.010] [Citation(s) in RCA: 286] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2005] [Revised: 08/30/2005] [Accepted: 08/31/2005] [Indexed: 11/25/2022]
Abstract
Only oppositely charged ions with matching absolute free energies of hydration spontaneously form inner sphere ion pairs in free solution [K.D.Collins, Ions from the Hofmeister series and osmolytes: effects on proteins in solution and in the crystallization process, Methods 34 (2004) 300-311.]. We approximate this with a Law of Matching Water Affinities which is used to examine the issues of (1) how ions are selected to be compatible with the high solubility requirements of cytosolic components; (2) how cytosolic components tend to interact weakly, so that association or dissociation can be driven by environmental signals; (3) how polyelectrolytes (nucleic acids) differ from isolated charges (in proteins); (4) how ions, osmolytes and polymers are used to crystallize proteins; and (5) how the "chelate effect" is used by macromolecules to bind ions at specific sites even when there is a mismatch in water affinity between the ion and the macromolecular ligands.
Collapse
Affiliation(s)
- Kim D Collins
- Department of Biochemistry and Molecular Biology, University of Maryland Medical School, 108 N. Greene Street, Baltimore, MD 21201-1503, USA.
| |
Collapse
|
235
|
Provis J, Duxson P, Van Deventer J, Lukey G. The Role of Mathematical Modelling and Gel Chemistry in Advancing Geopolymer Technology. Chem Eng Res Des 2005. [DOI: 10.1205/cherd.04329] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
236
|
Di Stasio E. Anionic regulation of biological systems: the special role of chloride in the coagulation cascade. Biophys Chem 2005; 112:245-52. [PMID: 15572255 DOI: 10.1016/j.bpc.2004.07.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2004] [Accepted: 07/01/2004] [Indexed: 10/26/2022]
Abstract
The discovery that previously unidentified allosteric properties of several proteins, such as fibrinogen and myoglobin, can be triggered by anions binding, has suggested the possibility to design a new "active" role of chloride in the modulation of a broad range of biological systems. The molecular bases of the anions binding to proteins depends by their charge density in turn regulating the ability to bind water molecules and interact with basic groups on proteins. This review reports the role of the physiologically relevant chloride, and of other anions, in the regulation of several proteins, with special attention to the coagulation cascade. Moreover, possible mechanisms of modification of plasma, intra- or extracellular chloride concentration are listed.
Collapse
Affiliation(s)
- Enrico Di Stasio
- Istituto di Biochimica e Biochimica Clinica, Università Cattolica del Sacro Cuore, Largo F. Vito no. 1, 00168 Rome, Italy.
| |
Collapse
|
237
|
Lo Nostro P, Ninham BW, Lo Nostro A, Pesavento G, Fratoni L, Baglioni P. Specific ion effects on the growth rates ofStaphylococcus aureusandPseudomonas aeruginosa. Phys Biol 2005; 2:1-7. [PMID: 16204851 DOI: 10.1088/1478-3967/2/1/001] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Motivated by recent advances in the physical and chemical basis of the Hofmeister effect, we measured the rate cell growth of S. aureus--a halophilic pathogenic bacterium--and of P. aeruginosa, an opportunistic pathogen, in the presence of different aqueous salt solutions at different concentrations (0.2, 0.6 and 0.9 M). Microorganism growth rates depend strongly on the kind of anion in the growth medium. In the case of S. aureus, chloride provides a favorable growth medium, while both kosmotropes (water structure makers) and chaotropes (water structure breakers) reduce the microorganism growth. In the case of P. aeruginosa, all ions affect adversely the bacterial survival. In both cases, the trends parallel the specific ion, or Hofmeister, sequences observed in a wide range of physico-chemical systems. The correspondence with specific ion effect obtained in other studies, on the activities of a DNA restriction enzyme, of horseradish peroxidase, and of Lipase A (Aspergillus niger) is particularly striking. This work provides compelling evidence for Hofmeister effects, physical chemistry in action, in these organisms.
Collapse
Affiliation(s)
- Pierandrea Lo Nostro
- Department of Chemistry and CSGI, University of Florence, via della Lastruccia 3-50019 Sesto Fiorentino (Firenze), Italy.
| | | | | | | | | | | |
Collapse
|
238
|
|
239
|
|