351
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Khvostichenko DS, Ng JJD, Perry SL, Menon M, Kenis PJA. Effects of detergent β-octylglucoside and phosphate salt solutions on phase behavior of monoolein mesophases. Biophys J 2014; 105:1848-59. [PMID: 24138861 DOI: 10.1016/j.bpj.2013.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2013] [Revised: 08/16/2013] [Accepted: 09/06/2013] [Indexed: 10/26/2022] Open
Abstract
Using small-angle x-ray scattering (SAXS), we investigated the phase behavior of mesophases of monoolein (MO) mixed with additives commonly used for the crystallization of membrane proteins from lipidic mesophases. In particular, we examined the effect of sodium and potassium phosphate salts and the detergent β-octylglucoside (βOG) over a wide range of compositions relevant for the crystallization of membrane proteins in lipidic mesophases. We studied two types of systems: 1), ternary mixtures of MO with salt solutions above the hydration boundary; and 2), quaternary mixtures of MO with βOG and salt solutions over a wide range of hydration conditions. All quaternary mixtures showed highly regular lyotropic phase behavior with the same sequence of phases (Lα, Ia3d, and Pn3m) as MO/water mixtures at similar temperatures. The effects of additives in quaternary systems agreed qualitatively with those found in ternary mixtures in which only one additive is present. However, quantitative differences in the effects of additives on the lattice parameters of fully hydrated mesophases were found between ternary and quaternary mixtures. We discuss the implications of these findings for mechanistic investigations of membrane protein crystallization in lipidic mesophases and for studies of the suitability of precipitants for mesophase-based crystallization methods.
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Affiliation(s)
- Daria S Khvostichenko
- Department of Chemical and Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois
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352
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Ganguly P, Hajari T, van der Vegt NFA. Molecular Simulation Study on Hofmeister Cations and the Aqueous Solubility of Benzene. J Phys Chem B 2014; 118:5331-9. [DOI: 10.1021/jp5011154] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Pritam Ganguly
- Center of
Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 10, 64287 Darmstadt, Germany
| | - Timir Hajari
- Center of
Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 10, 64287 Darmstadt, Germany
| | - Nico F. A. van der Vegt
- Center of
Smart Interfaces, Technische Universität Darmstadt, Alarich-Weiss-Straße 10, 64287 Darmstadt, Germany
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353
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Merk V, Rehbock C, Becker F, Hagemann U, Nienhaus H, Barcikowski S. In situ non-DLVO stabilization of surfactant-free, plasmonic gold nanoparticles: effect of Hofmeister's anions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:4213-22. [PMID: 24720469 DOI: 10.1021/la404556a] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Specific ion effects ranking in the Hofmeister sequence are ubiquitous in biochemical, industrial, and atmospheric processes. In this experimental study specific ion effects inexplicable by the classical DLVO theory have been investigated at curved water-metal interfaces of gold nanoparticles synthesized by a laser ablation process in liquid in the absence of any organic stabilizers. Notably, ion-specific differences in colloidal stability occurred in the Hückel regime at extraordinarily low salinities below 50 μM, and indications of a direct influence of ion-specific effects on the nanoparticle formation process are found. UV-vis, zeta potential, and XPS measurements help to elucidate coagulation properties, electrokinetic potential, and the oxidation state of pristine gold nanoparticles. The results clearly demonstrate that stabilization of ligand-free gold nanoparticles scales proportionally with polarizability and antiproportionally with hydration of anions located at defined positions in a direct Hofmeister sequence of anions. These specific ion effects might be due to the adsorption of chaotropic anions (Br(-), SCN(-), or I(-)) at the gold/water interface, leading to repulsive interactions between the partially oxidized gold particles during the nanoparticle formation process. On the other hand, kosmotropic anions (F(-) or SO4(2-)) seem to destabilize the gold colloid, whereas Cl(-) and NO3(-) give rise to an intermediate stability. Quantification of surface charge density indicated that particle stabilization is dominated by ion adsorption and not by surface oxidation. Fundamental insights into specific ion effects on ligand-free aqueous gold nanoparticles beyond purely electrostatic interactions are of paramount importance in biomedical or catalytic applications, since colloidal stability appears to depend greatly on the type of salt rather than on the amount.
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Affiliation(s)
- Vivian Merk
- Technical Chemistry I, University of Duisburg-Essen and Center for NanoIntegration Duisburg-Essen CENIDE , Universtitaetsstrasse 5, 45141 Essen, Germany
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354
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López-León T, Ortega-Vinuesa JL, Bastos-González D, Elaissari A. Thermally sensitive reversible microgels formed by poly(N-Isopropylacrylamide) charged chains: a Hofmeister effect study. J Colloid Interface Sci 2014; 426:300-7. [PMID: 24863797 DOI: 10.1016/j.jcis.2014.04.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 04/07/2014] [Accepted: 04/10/2014] [Indexed: 10/25/2022]
Abstract
In this study, we present a new method to obtain anionic and cationic stable colloidal nanogels from PNIPAM charged chains. The stability of the particles formed by inter-chain aggregation stems from the charged chemical groups attached at the sides of PNIPAM polymer chains. The particle formation is fully reversible-that is, it is possible to change from stable polymer solutions to stable colloidal dispersions and vice versa simply by varying temperature. In addition, we also demonstrate that the polymer LCST (lower critical solution temperature), the final particle size and the electrokinetic behavior of the particles formed are highly dependent on the electrolyte nature and salt concentration. These latter results are related to Hofmeister effects. The analysis of these results provides more insights about the origin of this ionic specificity, confirming that the interaction of ions with interfaces is dominated by the chaotropic/kosmotropic character of the ions and the hydrophobic/hydrophilic character of the surface in solution.
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Affiliation(s)
- Teresa López-León
- EC2M, UMR Gulliver CNRS-ESPCI 7083 - 10 Rue Vauquelin, F-75231 Paris Cedex 05, France
| | - Juan L Ortega-Vinuesa
- Biocolloid and Fluid Physics Group, Department of Applied Physics, University of Granada, Av. Fuentenueva S/N, 18071 Granada, Spain
| | - Delfi Bastos-González
- Biocolloid and Fluid Physics Group, Department of Applied Physics, University of Granada, Av. Fuentenueva S/N, 18071 Granada, Spain.
| | - Abdelhamid Elaissari
- University of Lyon, F-69622 Lyon, France; University of Lyon-1, Villeurbanne, CNRS, (UMR 5007), LAGEP-CPE-308G, 43 bd. du 11 Nov. 1918, F-69622 Villeurbanne, France
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355
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Nazrul Islam M, Sarker KC, Aktaruzzaman G. Effect of Electrolytes on the Krafft Temperature of Cetylpyridinium Chloride in Aqueous Solution. J SURFACTANTS DETERG 2014. [DOI: 10.1007/s11743-014-1577-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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356
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Ghimire C, Koirala D, Mathis MB, Kooijman EE, Mao H. Controlled particle collision leads to direct observation of docking and fusion of lipid droplets in an optical trap. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:1370-1375. [PMID: 24447288 DOI: 10.1021/la404497v] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
As an intracellular organelle, phospholipid-coated lipid droplets have shown increasing importance due to their expanding biological functions other than the lipid storage. The growing biological significance necessitates a close scrutiny on lipid droplets, which have been proposed to mature in a cell through processes such as fusion. Unlike phospholipid vesicles that are well-known to fuse through docking and hemifusion steps, little is known on the fusion of lipid droplets. Herein, we used laser tweezers to capture two micrometer-sized 1,2,3-trioleoylglycerol (triolein) droplets coated with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) that closely resemble intracellular lipid droplets. We started the fusion processes by a well-controlled collision between the two lipid droplets in phosphate buffer at pH 7.4. By monitoring the change in the pathway of a trapping laser that captures the collided lipid droplets, docking and physical fusion events were clearly distinguished for the first time and their lifetimes were determined with a resolution of 10 μs after postsynchronization analysis. Our method revealed that the rate-limiting docking process is affected by anions according to a Hofmeister series, which sheds light on the important role of interfacial water shedding during the process. During the physical fusion, the kinetics between bare triolein droplets is faster than lipid droplets, suggesting that breaking of phospholipid coating is involved in the process. This scenario was further supported by direct observation of a short-lived hemifusion state with ∼46 ms lifetime in POPC-coated lipid droplets, but not in bare triolein droplets.
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Affiliation(s)
- Chiran Ghimire
- Department of Chemistry and Biochemistry and ‡Department of Biological Sciences, Kent State University , Kent, Ohio 44242, United States
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357
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Zhang R, Zhuang W. Cation effect in the ionic solution optical Kerr effect measurements: A simulation study. J Chem Phys 2014; 140:054507. [PMID: 24511952 DOI: 10.1063/1.4863696] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Ruiting Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, People's Republic of China
| | - Wei Zhuang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, People's Republic of China
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358
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Nitschke U, Stengel DB. Iodine contributes to osmotic acclimatisation in the kelp Laminaria digitata (Phaeophyceae). PLANTA 2014; 239:521-30. [PMID: 24253307 DOI: 10.1007/s00425-013-1992-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 10/28/2013] [Indexed: 06/02/2023]
Abstract
Iodide (I⁻) retained by the brown macroalga Laminaria digitata at millimolar levels, possesses antioxidant activities, but the wider physiological significance of its accumulation remains poorly understood. In its natural habitat in the lower intertidal, L. digitata experiences salinity changes and osmotic homeostasis is achieved by regulating the organic osmolyte mannitol. However, I⁻ may also holds an osmotic function. Here, impacts of hypo- and hypersaline conditions on I⁻ release from, and accumulation by, L. digitata were assessed. Additionally, mannitol accumulation was determined at high salinities, and physiological responses to externally elevated iodine concentrations and salinities were characterised by chl a fluorometry. Net I⁻ release rates increased with decreasing salinity. I⁻ was accumulated at normal (35 S A) and high salinities (50 S A); this coincided with enhanced rETRmax and qP causing pronounced photoprotection capabilities via NPQ. At 50 S A elevated tissue iodine levels impeded the well-established response of mannitol accumulation and prevented photoinhibition. Contrarily, low tissue iodine levels limited photoprotection capabilities and resulted in photoinhibition at 50 S A, even though mannitol was accumulated. The results indicate a, so far, undescribed osmotic function of I⁻ in L. digitata and, thus, multifunctional principles of this halogen in kelps. The osmotic function of mannitol may have been substituted by that of I⁻ under hypersaline conditions, suggesting a complementary role of inorganic and organic solutes under salinity stress. This study also provides first evidence that iodine accumulation in L. digitata positively affects photo-physiology.
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Affiliation(s)
- Udo Nitschke
- Botany and Plant Science, School of Natural Sciences, and Ryan Institute for Environmental, Marine and Energy Research, National University of Ireland Galway, Galway, Ireland,
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359
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Cassou CA, Williams ER. Anions in electrothermal supercharging of proteins with electrospray ionization follow a reverse Hofmeister series. Anal Chem 2014; 86:1640-7. [PMID: 24410546 PMCID: PMC3983018 DOI: 10.1021/ac403398j] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
![]()
The
effects of different anions on the extent of electrothermal
supercharging of proteins from aqueous ammonium and sodium salt solutions
were investigated. Sulfate and hydrogen phosphate are the most effective
anions at producing high charge state protein ions from buffered aqueous
solution, whereas iodide and perchlorate are ineffective with electrothermal
supercharging. The propensity for these anions to produce high charge
state protein ions follows the following trend: sulfate > hydrogen
phosphate > thiocyanate > bicarbonate > chloride > formate
≈
bromide > acetate > iodide > perchlorate. This trend correlates
with
the reverse Hofmeister series over a wide range of salt concentrations
(1 mM to 2 M) and with several physical properties, including solvent
surface tension, anion viscosity B-coefficient, and anion surface/bulk
partitioning coefficient, all of which are related to the Hofmeister
series. The effectiveness of electrothermal supercharging does not
depend on bubble formation, either from thermal degradation of the
buffer or from coalescence of dissolved gas. These results provide
evidence that the effect of different ions in the formation of high
charge state ions by electrothermal supercharging is largely a result
of Hofmeister effects on protein stability leading to protein unfolding
in the heated ESI droplet.
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Affiliation(s)
- Catherine A Cassou
- Department of Chemistry, University of California , Berkeley, California 94720-1460, United States
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360
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Smiatek J. Osmolyte Effects: Impact on the Aqueous Solution around Charged and Neutral Spheres. J Phys Chem B 2014; 118:771-82. [DOI: 10.1021/jp410261k] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Jens Smiatek
- Institut für
Computerphysik, Universität Stuttgart, D-70569 Stuttgart, Germany
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361
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Möller J, Grobelny S, Schulze J, Steffen A, Bieder S, Paulus M, Tolan M, Winter R. Specific anion effects on the pressure dependence of the protein–protein interaction potential. Phys Chem Chem Phys 2014; 16:7423-9. [DOI: 10.1039/c3cp55278k] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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362
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Cuellar KA, Munroe KL, Magers DH, Hammer NI. Noncovalent Interactions in Microsolvated Networks of Trimethylamine N-Oxide. J Phys Chem B 2013; 118:449-59. [DOI: 10.1021/jp408659n] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kristina A. Cuellar
- Department
of Chemistry and Biochemistry, University of Mississippi, P.O. Box 1848, University, Mississippi 38655, United States
| | - Katherine L. Munroe
- Department
of Chemistry and Biochemistry, Mississippi College, P.O. Box 4036, Clinton, Mississippi 39058, United States
| | - David H. Magers
- Department
of Chemistry and Biochemistry, Mississippi College, P.O. Box 4036, Clinton, Mississippi 39058, United States
| | - Nathan I. Hammer
- Department
of Chemistry and Biochemistry, University of Mississippi, P.O. Box 1848, University, Mississippi 38655, United States
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363
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Hua W, Verreault D, Allen HC. Surface Prevalence of Perchlorate Anions at the Air/Aqueous Interface. J Phys Chem Lett 2013; 4:4231-4236. [PMID: 26296170 DOI: 10.1021/jz402009f] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Air/aqueous interfaces provide a unique environment for many chemical, environmental, and biological processes. To gain insight, molecular-level understanding of the interfacial water organization and ion distributions at these interfaces is required. Here, the air/aqueous interface of NaClO4 salt solutions was investigated by means of conventional and heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectroscopy. It is found that perchlorate (ClO4(-)) ions exist in the interfacial region and prefer to reside on average above their counterions. This finding is inferred from the average orientation of the OH transition dipole moment of interfacial water molecules governed by the direction of the net electric field arising from the interfacial ion distributions. At the air/aqueous interface of NaClO4 salt solutions, the net dipole moments of hydrogen-bonded water molecules are oriented preferentially toward the vapor phase. Contrary to some other salts (e.g., sulfates), the presence of ClO4(-) may cause a full reversal in the direction of the interfacial electric field at a higher concentration (≥1.7 M). Another interpretation for the positive Im χ((2)) spectra of NaClO4 salt solutions could be an increase in the population of water species contributing positively to the net OH transition dipole moment. Regardless of the mechanism, this effect becomes even more pronounced with increasing salt concentration.
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364
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Abstract
In cells, biological molecules function in an aqueous solution. Electrolytes and other small molecules play important roles in keeping the osmotic pressure of the cellular environment as well as the structure formation and function of biomolecules. The observed empirical rules such as Hofmeister series are still waiting for molecular interpretations. In this Perspective, we will discuss a simple and self-consistent theory that takes into account the cooperative effects of cations and anions in affecting water/air surface tension, water activity, and the solubility of model compounds including polypeptides. Molecular dynamics simulations used to test these theoretical models will also be discussed.
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Affiliation(s)
- Wen Jun Xie
- Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
| | - Yi Qin Gao
- Institute of Theoretical and Computational Chemistry, College of Chemistry and Molecular Engineering, Peking National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
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365
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Ahmed M, Namboodiri V, Singh AK, Mondal JA, Sarkar SK. How Ions Affect the Structure of Water: A Combined Raman Spectroscopy and Multivariate Curve Resolution Study. J Phys Chem B 2013; 117:16479-85. [DOI: 10.1021/jp4100697] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Mohammed Ahmed
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
| | - V. Namboodiri
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
| | - Ajay K. Singh
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
| | - Jahur A. Mondal
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
| | - Sisir K. Sarkar
- Radiation & Photochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400085, India
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366
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Beecham MP, Clarkson GJ, Hall G, Marsh A. Nanostructures from self-assembling triazine tertiary amine N-oxide amphiphiles. Chemphyschem 2013; 14:3909-15. [PMID: 24203796 DOI: 10.1002/cphc.201300775] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Indexed: 11/08/2022]
Abstract
A new set of amphiphilic tertiary amine N-oxides has been prepared and their self-assembly properties observed in aqueous solution by tensiometry, dynamic and static light scattering. X-ray crystallographic analysis of parent amines and sulfoxide congeners indicates the formation of hydrogen-bonded dimers as the primary assembly unit for formation of vesicles in preference to the compact micelles typical of lauryl dimethylamine N-oxide (LDAO). 6-Benzyloxy-N,N'-bis(5-diethylaminopentylamine oxide)[1,3,5]triazine-2,4-diamine forms a 1 μm vesicle observed to entrap fluorescein. The [1,3,5]triazine core thus allows variation of the new self-assembled structures from nano- to micrometre length scales.
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Affiliation(s)
- Matthew P Beecham
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL (UK), Fax: (+44) 24 7652 4112
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367
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Sepasi Tehrani H, Moosavi-Movahedi A, Ghourchian H, Ahmad F, Kiany A, Atri M, Ariaeenejad S, Kavousi K, Saboury A. Effect of compatible and noncompatible osmolytes on the enzymatic activity and thermal stability of bovine liver catalase. J Biomol Struct Dyn 2013; 31:1440-54. [DOI: 10.1080/07391102.2012.742460] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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368
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Ge A, Peng Q, Wu H, Liu H, Tong Y, Nishida T, Yoshida N, Suzuki K, Sakai T, Osawa M, Ye S. Effect of functional group on the monolayer structures of biodegradable quaternary ammonium surfactants. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:14411-14420. [PMID: 24156383 DOI: 10.1021/la403502k] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The monolayer structures and conformational ordering of cationic surfactants including the biodegradable quaternary ammonium molecules have been systematically characterized by π-A isotherm, surface potential, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and sum frequency generation (SFG) vibrational spectroscopy. It was found that the monolayer of the typical dialkyl dimethylammonium on the water surface was less densely packed along with many conformational gauche defects. The packing density and ordering of these monolayers were improved as halide ions were added to the subphase. A similar condensation effect was also observed when amide or ester groups are present in the alkyl tails of the surfactant. These results are discussed on the basis of the repulsive electrostatic interactions between the terminal ammonium moieties, the hydrogen bonding between the functional groups in the alkyl chains, as well as the flexibility of the alkyl chains in these surfactants. The present study is crucial to understanding the relationship between the interfacial structures and the functionalities of the biodegradable quaternary ammonium surfactants.
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Affiliation(s)
- Aimin Ge
- Catalysis Research Center, Hokkaido University , Sapporo 001-0021, Japan
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369
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McCarley RL, Forsythe JC, Loew M, Mendoza MF, Hollabaugh NM, Winter JE. Release rates of liposomal contents are controlled by kosmotropes and chaotropes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:13991-5. [PMID: 24160736 PMCID: PMC3932753 DOI: 10.1021/la402740k] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Contents release from redox-responsive liposomes is anion-specific. Liposomal contents release is initiated by the contact of apposed liposome bilayers having in their outer leaflet 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), whose presence is due to the redox-stimulated removal of a quinone propionic acid protecting group (Q) from Q-DOPE lipids. Contents release occurs upon the phase transition of DOPE from its lamellar liquid-crystalline phase (Lα) to its hexagonal-II inverted micelle (HII) phase. Contents release is slower in the presence of weakly hydrated chaotropic anions versus highly hydrated kosmotropic anions and is attributed to ion accumulation near the zwitterionic DOPE headgroups, in turn altering the headgroup hydration, as indicated by the Lα → HII phase transition temperature, TH, for DOPE. The results are significant, not only for mechanistic aspects of liposome contents release in DOPE-based systems but also for drug delivery applications wherein exist at drug targeting sites variations in the type and concentration of ions and neutral species.
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370
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Xie W, Liu C, Yang L, Gao Y. On the molecular mechanism of ion specific Hofmeister series. Sci China Chem 2013. [DOI: 10.1007/s11426-013-5019-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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371
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Kumar A, Venkatesu P. Does the stability of proteins in ionic liquids obey the Hofmeister series? Int J Biol Macromol 2013; 63:244-53. [PMID: 24211268 DOI: 10.1016/j.ijbiomac.2013.10.031] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 10/23/2013] [Accepted: 10/24/2013] [Indexed: 11/27/2022]
Abstract
Understanding the behavior of Hofmeister anions of ionic liquids (ILs) on protein stability helps to shed light on how the anions interact with proteins in aqueous solution and is a long standing object for chemistry and biochemistry. Ions effects play a major role in understanding the physicochemical and biological phenomenon that undertakes the protein folding/unfolding and refolding process. Despite the generality of these effects, our understanding of ions at the molecular-level is still limited. This review offers a tour through past successful investigations and presents a challenge in current research in the field to reassess the possibilities of ions and to apply new strategies. This review highlights on the stability behavior of the proteins and also comparisons of our past research work in the Hofmeister series of ILs. Furthermore, we specifically focus on the critical discussion on the recent findings with existing results and their implications, along with our understanding of the Hofmeister series of anions of ILs on biomolecular stability. A detailed examination of the difference between selective proteins can provide a better understanding of the molecular mechanism of protein folding/unfolding in the presence of the Hofmeister series of ions of ILs.
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Affiliation(s)
- Awanish Kumar
- Department of Chemistry, University of Delhi, Delhi 110 007, India
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372
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Smith BM, Bean SR, Selling G, Sessa D, Aramouni FM. Role of non-covalent interactions in the production of visco-elastic material from zein. Food Chem 2013; 147:230-8. [PMID: 24206711 DOI: 10.1016/j.foodchem.2013.09.152] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/25/2013] [Accepted: 09/30/2013] [Indexed: 10/26/2022]
Abstract
The role of non-covalent interactions in the formation of visco-elastic material from zein was investigated. Hydrophobic interactions were evaluated through the addition of various salts from the Hofmeister series. Urea, ethanol, and beta mercaptoethanol (β-ME) were used to evaluate the effects of protein denaturation and disulfide bonds on zein's ability to form a visco-elastic material. The addition of NaI and NaSCN altered the properties of visco-elastic materials made from zein, making them softer and more extensible, as did urea and ethanol. The addition of NaCl and Na2SO4 negatively impacted the ability of zein to from a visco-elastic material and at higher concentrations completely disrupted the formation of visco-elastic material. These results indicate that manipulating non-covalent interactions in zein can alter and in some cases, completely disrupt the formation of a visco-elastic material. Specifically this may be due to disruption of hydrophobic interactions within individual zein proteins or interactions between proteins. The reducing agent β-ME had little effect on zein's ability to form a visco-elastic material. Therefore, the visco-elastic properties of zein arise as a result of non-covalent interactions.
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Affiliation(s)
- Brennan M Smith
- USDA-ARS Center for Grain and Animal Health Research, 1515 College Ave., Manhattan, KS 66502, USA.
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373
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Franck JM, Pavlova A, Scott JA, Han S. Quantitative cw Overhauser effect dynamic nuclear polarization for the analysis of local water dynamics. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2013; 74:33-56. [PMID: 24083461 PMCID: PMC3798041 DOI: 10.1016/j.pnmrs.2013.06.001] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 01/10/2013] [Indexed: 05/03/2023]
Abstract
Liquid state Overhauser effect Dynamic Nuclear Polarization (ODNP) has experienced a recent resurgence of interest. The ODNP technique described here relies on the double resonance of electron spin resonance (ESR) at the most common, i.e. X-band (∼10GHz), frequency and ¹H nuclear magnetic resonance (NMR) at ∼15 MHz. It requires only a standard continuous wave (cw) ESR spectrometer with an NMR probe inserted or built into an X-band cavity. We focus on reviewing a new and powerful manifestation of ODNP as a high frequency NMR relaxometry tool that probes dipolar cross relaxation between the electron spins and the ¹H nuclear spins at X-band frequencies. This technique selectively measures the translational mobility of water within a volume extending 0.5-1.5 nm outward from a nitroxide radical spin probe that is attached to a targeted site of a macromolecule. It allows one to study the dynamics of water that hydrates or permeates the surface or interior of proteins, polymers, and lipid membrane vesicles. We begin by reviewing the recent advances that have helped develop ODNP into a tool for mapping the dynamic landscape of hydration water with sub-nanometer locality. In order to bind this work coherently together and to place it in the context of the extensive body of research in the field of NMR relaxometry, we then rephrase the analytical model and extend the description of the ODNP-derived NMR signal enhancements. This extended model highlights several aspects of ODNP data analysis, including the importance of considering all possible effects of microwave sample heating, the need to consider the error associated with various relaxation rates, and the unique ability of ODNP to probe the electron-¹H cross-relaxation process, which is uniquely sensitive to fast (tens of ps) dynamical processes. By implementing the relevant corrections in a stepwise fashion, this paper draws a consensus result from previous ODNP procedures and then shows how such data can be further corrected to yield clear and reproducible saturation of the NMR hyperpolarization process. Finally, drawing on these results, we broadly survey the previous ODNP dynamics literature. We find that the vast number of published, empirical hydration dynamics data can be reproducibly classified into regimes of surface, interfacial, vs. buried water dynamics.
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Affiliation(s)
- John M Franck
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
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374
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Bye JW, Falconer RJ. Thermal stability of lysozyme as a function of ion concentration: a reappraisal of the relationship between the Hofmeister series and protein stability. Protein Sci 2013; 22:1563-70. [PMID: 24038575 DOI: 10.1002/pro.2355] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 08/14/2013] [Accepted: 08/19/2013] [Indexed: 11/09/2022]
Abstract
Anion and cation effects on the structural stability of lysozyme were investigated using differential scanning calorimetry. At low concentrations (<5 mM) anions and cations alter the stability of lysozyme but they do not follow the Hofmeister (or inverse Hofmeister) series. At higher concentrations protein stabilization follows the well-established Hofmeister series. Our hypothesis is that there are three mechanisms at work. At low concentrations the anions interact with charged side chains where the presence of the ion can alter the structural stability of the protein. At higher concentrations the low charge density anions perchlorate and iodide interact weakly with the protein. Their presence however reduces the Gibbs free energy required to hydrate the core of the protein that is exposed during unfolding therefore destabilizing the structure. At higher concentrations the high charge density anions phosphate and sulfate compete for water with the protein as it unfolds increasing the Gibbs free energy required to hydrate the newly exposed core of the protein therefore stabilizing the structure.
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Affiliation(s)
- Jordan W Bye
- Department of Chemical and Biological Engineering, ChELSI Institute, University of Sheffield, Sheffield, S1 3JD, England, United Kingdom
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375
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Hua Y, Liu Y, Chen CH, Flood AH. Hydrophobic collapse of foldamer capsules drives picomolar-level chloride binding in aqueous acetonitrile solutions. J Am Chem Soc 2013; 135:14401-12. [PMID: 24028552 DOI: 10.1021/ja4074744] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Aqueous media are competitive environments in which to perform host-guest chemistry, particularly when the guest is highly charged. While hydrophobic binding is a recognized approach to this challenge in which apolar pockets can be designed to recognize apolar guests in water, complementary strategies are required for hydrophilic anions like chloride. Here, we present evidence of such an alternative mechanism, used everyday by proteins yet rare for artificial receptors, wherein hydrophobic interactions are shown to be responsible for organizing and stabilizing an aryl-triazole foldamer to help extract hydrophilic chloride ions from increasingly aqueous solutions. Therein, a double-helical complex gains stability upon burial of ∼80% of the π surfaces that simultaneously creates a potent, solvent-excluding microenvironment for hydrogen bonding. The chloride's overall affinity to the duplex is substantial in 25% water v/v in acetonitrile (log β2 = 12.6), and it remains strong (log β2 = 13.0) as the water content is increased to 50%. With the rise in predictable designs of abiological foldamers, this water-assisted strategy can, in principle, be utilized for binding other hydrophilic guests.
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Affiliation(s)
- Yuran Hua
- Department of Chemistry, Indiana University , 800 East Kirkwood Avenue, Bloomington, Indiana 47405, United States
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376
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Xu D, Chen X, Wang L, Qiu L, Zhang H, Yan F. Performance enhancement for high performance dye-sensitized solar cells via using pyridinyl-functionalized ionic liquid type additive. Electrochim Acta 2013. [DOI: 10.1016/j.electacta.2013.05.091] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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377
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Tavagnacco L, Brady JW, Cesàro A. The Interaction of Sorbitol with Caffeine in Aqueous Solution. FOOD BIOPHYS 2013; 8:216-222. [PMID: 24000279 DOI: 10.1007/s11483-013-9290-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Molecular dynamics simulations were carried out on a system of caffeine interacting with the sugar alcohol sorbitol. The system examined had a caffeine concentration 0.083 m and a sugar concentration 1.08 m. The trajectories of all molecules in the system were collected over a period of 80 ns and analyzed to determine whether there is any tendency for sorbitol to bind to caffeine, and if so, by what mechanism. The results show that the sorbitol molecules have an affinity for the caffeine molecules and that the binding occurred by the interaction of the aliphatic hydrophobic protons of the sugar with the caffeine face. This intermolecular association via face-to-face stacking, as suggested by simulation studies, is similar to that found for sucrose and for D-glucose, which overwhelmingly exists in the pyranose ring chair form in aqueous solution, as well as for caffeine-caffeine association. The sorbitol molecules, however, exist as relatively extended chains and are, therefore, topologically quite different from the sugars sucrose and glucose. The comparison of the average conformation of sorbitol molecules bound to caffeine with that of molecules in the free state shows a substantial similarity.
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Affiliation(s)
- Letizia Tavagnacco
- Department of Food Science, Cornell University, Ithaca, NY 14853 ; Department of Life Sciences, University of Trieste, Trieste, ITALY
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378
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Bae S, Son H, Kim YG, Hohng S. Z-DNA stabilization is dominated by the Hofmeister effect. Phys Chem Chem Phys 2013; 15:15829-32. [PMID: 23995025 DOI: 10.1039/c3cp52047a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The manner in which Z-DNA is stabilized at high salt concentrations remains unclear. Here, we systematically examine the Z-DNA-stabilizing capabilities of different salts. The strong correlation between the double-stranded DNA denaturation and B-to-Z transition efficiencies indicates that Z-DNA is mainly stabilized by the Hofmeister effect.
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Affiliation(s)
- Sangsu Bae
- Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea.
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379
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Lutter JC, Wu TY, Zhang Y. Hydration of Cations: A Key to Understanding of Specific Cation Effects on Aggregation Behaviors of PEO-PPO-PEO Triblock Copolymers. J Phys Chem B 2013; 117:10132-41. [DOI: 10.1021/jp405709x] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jacob C. Lutter
- Department of Chemistry and
Biochemistry, James Madison University, Harrisonburg, Virginia 22807, United States
| | - Tsung-yu Wu
- Department of Chemistry and
Biochemistry, James Madison University, Harrisonburg, Virginia 22807, United States
| | - Yanjie Zhang
- Department of Chemistry and
Biochemistry, James Madison University, Harrisonburg, Virginia 22807, United States
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380
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Zhang R, Zhuang W. Effect of Ion Pairing on the Solution Dynamics Investigated by the Simulations of the Optical Kerr Effect and the Dielectric Relaxation Spectra. J Phys Chem B 2013; 117:15395-406. [DOI: 10.1021/jp404923y] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- Ruiting Zhang
- State Key
Lab of Molecular Reaction Dynamics, Dalian
Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Wei Zhuang
- State Key
Lab of Molecular Reaction Dynamics, Dalian
Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
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381
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Sun Z, Zhang W, Ji M, Hartsock R, Gaffney KJ. Contact Ion Pair Formation between Hard Acids and Soft Bases in Aqueous Solutions Observed with 2DIR Spectroscopy. J Phys Chem B 2013; 117:15306-12. [DOI: 10.1021/jp4033854] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Zheng Sun
- PULSE Institute, SLAC National Accelerator
Laboratory, Stanford University, Stanford,
California 94305, United
States
| | - Wenkai Zhang
- PULSE Institute, SLAC National Accelerator
Laboratory, Stanford University, Stanford,
California 94305, United
States
| | - Minbiao Ji
- PULSE Institute, SLAC National Accelerator
Laboratory, Stanford University, Stanford,
California 94305, United
States
| | - Robert Hartsock
- PULSE Institute, SLAC National Accelerator
Laboratory, Stanford University, Stanford,
California 94305, United
States
| | - Kelly J. Gaffney
- PULSE Institute, SLAC National Accelerator
Laboratory, Stanford University, Stanford,
California 94305, United
States
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382
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Carr JK, Buchanan LE, Schmidt JR, Zanni MT, Skinner JL. Structure and dynamics of urea/water mixtures investigated by vibrational spectroscopy and molecular dynamics simulation. J Phys Chem B 2013; 117:13291-300. [PMID: 23841646 DOI: 10.1021/jp4037217] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Urea/water is an archetypical "biological" mixture and is especially well-known for its relevance to protein thermodynamics as urea acts as a protein denaturant at high concentration. This behavior has given rise to an extended debate concerning urea's influence on water structure. On the basis of a variety of methods and of definitions of the water structure, urea has been variously described as a structure-breaker, a structure-maker, or as remarkably neutral toward water. Because of its sensitivity to microscopic structure and dynamics, vibrational spectroscopy can help resolve these debates. We report experimental and theoretical spectroscopic results for the OD stretch of HOD/H2O/urea mixtures (linear IR, 2DIR, and pump-probe anisotropy decay) and for the CO stretch of urea-D4/D2O mixtures (linear IR only). Theoretical results are obtained using existing approaches for water and a modification of a frequency map developed for acetamide. All absorption spectra are remarkably insensitive to urea concentration, consistent with the idea that urea only very weakly perturbs the water structure. Both this work and experiments by Rezus and Bakker, however, show that water's rotational dynamics are slowed down by urea. Analysis of the simulations casts doubt on the suggestion that urea immobilizes particular doubly hydrogen bonded water molecules.
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Affiliation(s)
- J K Carr
- Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin , Madison, Wisconsin 53706, United States
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383
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Papanyan Z, Roth C, Wittler K, Reimann S, Ludwig R. The Dissolution of Polyols in Salt Solutions and Ionic Liquids at Molecular Level: Ions, Counter Ions, and Hofmeister Effects. Chemphyschem 2013; 14:3667-71. [DOI: 10.1002/cphc.201300465] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2013] [Indexed: 11/12/2022]
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384
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Abstract
Hofmeister effects are part of a larger story--one in which the devil is perhaps in the details, but which promises to give us a much deeper understanding of how the solvent is a part of cell and molecular biology.
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385
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Lee J, Lin EW, Lau UY, Hedrick JL, Bat E, Maynard HD. Trehalose glycopolymers as excipients for protein stabilization. Biomacromolecules 2013; 14:2561-9. [PMID: 23777473 DOI: 10.1021/bm4003046] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Herein, the synthesis of four different trehalose glycopolymers and investigation of their ability to stabilize proteins to heat and lyophilization stress are described. The disaccharide, α,α-trehalose, was modified with a styrenyl acetal, methacrylate acetal, styrenyl ether, or methacrylate moiety resulting in four different monomers. These monomers were then separately polymerized using free radical polymerization with azobisisobutyronitrile (AIBN) as an initiator to synthesize the glycopolymers. Horseradish peroxidase and glucose oxidase were incubated at 70 and 50 °C, respectively, and β-galactosidase was lyophilized multiple times in the presence of various ratios of the polymers or trehalose. The protein activities were subsequently tested and found to be significantly higher when the polymers were present during the stress compared to no additive and to equivalent amounts of trehalose. Different molecular weights (10 kDa, 20 kDa, and 40 kDa) were tested, and all were equivalent in their stabilization ability. However, some subtle differences were observed regarding stabilization ability between the different polymer samples, depending on the stress. Small molecules such as benzyl ether trehalose were not better stabilizers than trehalose, and the trehalose monomer decreased protein activity, suggesting that hydrophobized trehalose was not sufficient and that the polymeric structure was required. In addition, cytotoxicity studies with NIH 3T3 mouse embryonic fibroblast cells, RAW 264.7 murine macrophages, human dermal fibroblasts (HDFs), and human umbilical vein endothelial cells (HUVECs) were conducted with polymer concentrations up to 8 mg/mL. The data showed that all four polymers were noncytotoxic for all tested concentrations. The results together suggest that trehalose glycopolymers are promising as additives to protect proteins from a variety of stressors.
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Affiliation(s)
- Juneyoung Lee
- Department of Chemistry & Biochemistry, University of California, Los Angeles, 90095, USA
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386
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Jahangiri S, Mercer SM, Jessop PG, Peslherbe GH. Computational Investigation of the Hydration of Alkyl Diammonium Chlorides and Their Effect on THF/Water Phase Separation. J Phys Chem B 2013; 117:8010-7. [DOI: 10.1021/jp403984q] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Soran Jahangiri
- Centre for Research in Molecular
Modeling (CERMM) and Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke Street West,
Montréal, Québec, Canada H4B 1R6
| | - Sean M. Mercer
- Department of Chemistry, Queen’s University, 90 Bader Lane, Kingston,
Ontario, Canada K7L 3N6
| | - Philip G. Jessop
- Department of Chemistry, Queen’s University, 90 Bader Lane, Kingston,
Ontario, Canada K7L 3N6
| | - Gilles H. Peslherbe
- Centre for Research in Molecular
Modeling (CERMM) and Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke Street West,
Montréal, Québec, Canada H4B 1R6
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387
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Rankin BM, Ben-Amotz D. Expulsion of Ions from Hydrophobic Hydration Shells. J Am Chem Soc 2013; 135:8818-21. [PMID: 23734747 DOI: 10.1021/ja4036303] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Blake M. Rankin
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette,
Indiana 47906, United States
| | - Dor Ben-Amotz
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette,
Indiana 47906, United States
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388
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Characterising protein, salt and water interactions with combined vibrational spectroscopic techniques. Food Chem 2013; 138:679-86. [DOI: 10.1016/j.foodchem.2012.10.117] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2012] [Revised: 10/11/2012] [Accepted: 10/16/2012] [Indexed: 11/21/2022]
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389
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Hou B, Laanait N, Yu H, Bu W, Yoon J, Lin B, Meron M, Luo G, Vanysek P, Schlossman ML. Ion Distributions at the Water/1,2-Dichloroethane Interface: Potential of Mean Force Approach to Analyzing X-ray Reflectivity and Interfacial Tension Measurements. J Phys Chem B 2013; 117:5365-78. [DOI: 10.1021/jp401892y] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Binyang Hou
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois
60607, United States
| | - Nouamane Laanait
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois
60607, United States
| | - Hao Yu
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois
60607, United States
| | - Wei Bu
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois
60607, United States
| | - Jaesung Yoon
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois
60607, United States
| | - Binhua Lin
- The
Center for Advanced Radiation
Sources, University of Chicago, Chicago,
Illinois 60637, United States
| | - Mati Meron
- The
Center for Advanced Radiation
Sources, University of Chicago, Chicago,
Illinois 60637, United States
| | - Guangming Luo
- BSRF, Institute of High Energy
Physics, Chinese Academy of Sciences, Beijing,
100049, China
| | - Petr Vanysek
- Department of Chemistry & Biochemistry, Northern Illinois University, DeKalb, Illinois 60115, United States
| | - Mark L. Schlossman
- Department of Physics, University of Illinois at Chicago, Chicago, Illinois
60607, United States
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390
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Llamas S, Mendoza AJ, Guzmán E, Ortega F, Rubio RG. Salt effects on the air/solution interfacial properties of PEO-containing copolymers: equilibrium, adsorption kinetics and surface rheological behavior. J Colloid Interface Sci 2013; 400:49-58. [PMID: 23582902 DOI: 10.1016/j.jcis.2013.03.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 03/05/2013] [Accepted: 03/06/2013] [Indexed: 10/27/2022]
Abstract
Lithium cations are known to form complexes with the oxygen atoms of poly(oxyethylene) chains. The effect of Li(+) on the surface properties of three block-copolymers containing poly(oxyethylene) (PEO) have been studied. Two types of copolymers have been studied, a water soluble one of the pluronic family, PEO-b-PPO-b-PEO, PPO being poly(propyleneoxyde), and two water insoluble ones: PEO-b-PS and PEO-b-PS-b-PEO, PS being polystyrene. In the case of the pluronic the adsorption kinetics, the equilibrium surface tension isotherm and the aqueous/air surface rheology have been measured, while for the two insoluble copolymers only the surface pressure and the surface rheology have been studied. In all the cases two different Li(+) concentrations have been used. As in the absence of lithium ions, the adsorption kinetics of pluronic solutions shows two processes, and becomes faster as [Li(+)] increases. The kinetics is not diffusion controlled. For a given pluronic concentration the equilibrium surface pressure increases with [Li(+)], and the isotherms show two surface phase transitions, though less marked than for [Li(+)]=0. A similar behavior was found for the equilibrium isotherms of PEO-b-PS and PEO-b-PS-b-PEO. The surface elasticity of these two copolymers was found to increase with [Li(+)] over the whole surface concentration and frequency ranges studied. A smaller effect was found in the case of the pluronic solutions. The results of the pluronic solutions were modeled using a recent theory that takes into account that the molecules can be adsorbed at the surface in two different states. The theory gives a good fit for the adsorption kinetics and a reasonably good prediction of the equilibrium isotherms for low and intermediate concentrations of pluronic. However, the theory is not able to reproduce the isotherm for [Li(+)]=0. Only a semi-quantitative prediction of the surface elasticity is obtained for [pluronic]≤1×10(-3) mM.
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Affiliation(s)
- Sara Llamas
- Departamento de Química Física I, Facultad de Química, Universidad Complutense de Madrid, 28040 Madrid, Spain
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391
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Okur HI, Kherb J, Cremer PS. Cations Bind Only Weakly to Amides in Aqueous Solutions. J Am Chem Soc 2013; 135:5062-7. [DOI: 10.1021/ja3119256] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Halil I. Okur
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Jaibir Kherb
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Paul S. Cremer
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
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392
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Schwierz N, Horinek D, Netz RR. Anionic and cationic Hofmeister effects on hydrophobic and hydrophilic surfaces. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2013; 29:2602-14. [PMID: 23339330 DOI: 10.1021/la303924e] [Citation(s) in RCA: 175] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Using a two-step modeling approach, we address the full spectrum of direct, reversed, and altered ionic sequences as the charge of the ion, the charge of the surface, and the surface polarity are varied. From solvent-explicit molecular dynamics simulations, we extract single-ion surface interaction potentials for halide and alkali ions at hydrophilic and hydrophobic surfaces. These are used within Poisson-Boltzmann theory to calculate ion density and electrostatic potential distributions at mixed polar/unpolar surfaces for varying surface charge. The resulting interfacial tension increments agree quantitatively with experimental data and capture the Hofmeister series, especially the anomaly of lithium, which is difficult to obtain using continuum theory. Phase diagrams that feature different Hofmeister series as a function of surface charge, salt concentration, and surface polarity are constructed from the long-range force between two surfaces interacting across electrolyte solutions. Large anions such as iodide have a high hydrophobic surface affinity and increase the effective charge magnitude on negatively charged unpolar surfaces. Large cations such as cesium also have a large hydrophobic surface affinity and thereby compensate an external negative charge surface charge most efficiently, which explains the well-known asymmetry between cations and anions. On the hydrophilic surface, the size-dependence of the ion surface affinity is reversed, explaining the Hofmeister series reversal when comparing hydrophobic with hydrophilic surfaces.
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Affiliation(s)
- Nadine Schwierz
- Fachbereich für Physik, Freie Universität Berlin, 141954 Berlin, Germany
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393
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Heyda J, Muzdalo A, Dzubiella J. Rationalizing Polymer Swelling and Collapse under Attractive Cosolvent Conditions. Macromolecules 2013. [DOI: 10.1021/ma302320y] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jan Heyda
- Soft Matter
and Functional Materials, Helmholtz-Zentrum Berlin, Hahn-Meitner Platz 1, 14109
Berlin, Germany, and Department of Physics, Humboldt-University Berlin, Newtonstr. 15, 12489 Berlin, Germany
| | - Anja Muzdalo
- Soft Matter
and Functional Materials, Helmholtz-Zentrum Berlin, Hahn-Meitner Platz 1, 14109
Berlin, Germany, and Department of Physics, Humboldt-University Berlin, Newtonstr. 15, 12489 Berlin, Germany
| | - Joachim Dzubiella
- Soft Matter
and Functional Materials, Helmholtz-Zentrum Berlin, Hahn-Meitner Platz 1, 14109
Berlin, Germany, and Department of Physics, Humboldt-University Berlin, Newtonstr. 15, 12489 Berlin, Germany
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394
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