Home About us Contact
|
Home About us Contact | ||
|
|
||
Attractive Interactions (attractive + interaction)
Selected AbstractsWeak Attractive Interactions between Methylthio Groups and Electron-Deficient Alkenes in peri -Naphthalenes: A Competition with Conjugative EffectsCHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2006Jane O'Leary Dr. Abstract The solid-state conformations of five peri -disubstituted naphthalenes bearing a methylthio group and an electron-deficient alkene indicate a weak attractive interaction between the functional groups in four cases in which out-of-plane displacements lead to a common orientation of the MeS,,,sp2 -C vector to the alkene bond. In some cases the interaction is not strong enough to outweigh the tendency of the alkene to conjugate with the aromatic ring, and in one case this optimisation of conjugation alone controls the molecular conformation. The methylthio group lies close to the aromatic plane in all but one example for which the plane of the sulfide group is presented to the alkene. [source] Orientation of endohedral H2, CO, and LiH inside heptagon-containing C58 and C58H18INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 5 2010Lili Sun Abstract Three H2@C58Hx, six CO@C58Hx, and six LiH@C58Hx (x = 0 and 18) complexes were optimized using B3LYP/6-31G* method. The results show that both C58 and C58H18 destabilize nonpolar H2 and weakly polar CO, and stabilize strongly polar LiH inside their cages. Three H2@C58Hx (x = 0 and 18) complexes are nearly equivalent in energy, and CO orients the longest direction of cage because of spatial repulsion between them in the most stable CO@C58Hx (x = 0 and 18) isomers. Orientation of LiH inside C58Hx (x = 0 and 18) cages is determined by dipole-induced dipole attractive interaction between them, and this attraction is especially significant in LiH@C58H18 complexes. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010 [source] Ab initio study of spinodal decomposition in (Zn, Cr)TePHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2006T. Fukushima Abstract The spinodal decomposition in (Zn, Cr)Te is simulated by using first principles calculations and Monte Carlo simulation. It is found that the chemical pair interaction between Cr atoms in (Zn, Cr)Te is attractive interaction and leads to spinodal decomposition. Curie temperatures in decomposed situation are estimated by the random phase approximation with taking the magnetic percolation effect into account. This decomposed phase makes the random pattern of high concentration regions which connect each other and have possibility to realize high Curie temperature. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Interacting bosons in an optical latticeANNALEN DER PHYSIK, Issue 8 2008C. Moseley Abstract A strongly interacting Bose gas in an optical lattice is studied using a hard-core interaction. Two different approaches are introduced, one is based on a spin-1/2 Fermi gas with attractive interaction, the other one on a functional integral with an additional constraint (slave-boson approach). The relation between fermions and hard-core bosons is briefly discussed for the case of a one-dimensional Bose gas. For a three-dimensional gas we identify the order parameter of the Bose-Einstein condensate through a Hubbard-Stratonovich transformation and treat the corresponding theories within a mean-field approximation and with Gaussian fluctuations. This allows us to evaluate the phase diagram, including the Bose-Einstein condensate and the Mott insulator, the density-density correlation function, the static structure factor, and the quasiparticle excitation spectrum. The role of quantum and thermal fluctuations are studied in detail for both approaches, where we find good agreement with the Gross-Pitaevskii equation and with the Bogoliubov approach in the dilute regime. In the dense regime, which is characterized by the phase transition between the Bose-Einstein condensate and the Mott insulator, we discuss a renormalized Gross-Pitaevskii equation. This equation can describe the macroscopic wave function of the Bose-Einstein condensate in the dilute regime as well as close to the transition to the Mott insulator. Finally, we compare the results of the attractive spin-1/2 Fermi gas and those of the slave-boson approach and find good agreement for all physical quantities. [source] Weak Attractive Interactions between Methylthio Groups and Electron-Deficient Alkenes in peri -Naphthalenes: A Competition with Conjugative EffectsCHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2006Jane O'Leary Dr. Abstract The solid-state conformations of five peri -disubstituted naphthalenes bearing a methylthio group and an electron-deficient alkene indicate a weak attractive interaction between the functional groups in four cases in which out-of-plane displacements lead to a common orientation of the MeS,,,sp2 -C vector to the alkene bond. In some cases the interaction is not strong enough to outweigh the tendency of the alkene to conjugate with the aromatic ring, and in one case this optimisation of conjugation alone controls the molecular conformation. The methylthio group lies close to the aromatic plane in all but one example for which the plane of the sulfide group is presented to the alkene. [source] An Improvement in the Bending Ability of a Hinged Trisaccharide with the Assistance of a Sugar,,Sugar InteractionCHEMISTRY - A EUROPEAN JOURNAL, Issue 22 2005Hideya Yuasa Prof. Abstract Hinged di- and trisaccharides incorporating 2,4-diamino-,- D -xylopyranoside as a hinge unit (Hin) were synthesized. Bridging of the diamino group of Hin by carbonylation or chelation to a metal ion results in a conformational change from 4C1 to 1C4, which in turn causes a bending of the oligosaccharides. In this study, the bending abilities of the hinged oligosaccharides were compared, in terms of the reactivities toward carbonylation and chelation. Di- or trisaccharides containing a 6- O -glycosylated mannopyranoside or galactopyranoside at their reducing ends had bending abilities similar to that of the Hin monosaccharide, probably because there were neither attractive nor repulsive interactions between the reducing and nonreducing ends. However, when Hin was attached at O2 of methyl mannopyranoside (Man,Me), the bending ability was dependent on the nonreducing sugar and the reaction conditions. Typically, a disaccharide,Hin,(1,2)Man,Me,was difficult to bend under all the tested reaction conditions, and the bent population in the presence of ZnII was only 4,%. On the other hand, a trisaccharide,Man,(1,3)Hin,(1,2)Man,Me,was bent immediately after the addition of ZnII or HgII, and the bent population reached 75,%, much larger than those of all the other hinged trisaccharides ever tested (<40,%). This excellent bending ability suggests an attractive interaction between the reducing and nonreducing ends. The extended conformation was recovered by the addition of triethylenetetramine, a metal ion chelator. Reversible, quick, and efficient bending of the hinged trisaccharide was thus achieved. [source] Enhanced Stabilization of Reverse Micelles by Compressed CO2CHEMISTRY - A EUROPEAN JOURNAL, Issue 4 2005Dong Shen Dr. Abstract The effect of compressed CO2 on the solubilization capacity of water in reverse micelles of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in longer chain n -alkanes was studied at different temperatures and pressures. It was found that the amount of solubilized water is increased considerably by CO2 in a suitable pressure range. The suitable CO2 pressure range in which the solubilization capacity of water could be enhanced decreased with increasing W0 (water-to-AOT molar ratio). The microenvironments in the CO2 -stabilized reverse micelles were investigated by UV/Vis adsorption spectroscopy with methyl orange (MO) as probe. The mechanism by which the reverse micelles are stabilized by CO2 is discussed in detail. The main reason is likely to be that CO2 has a much smaller molecular volume than the n -alkane solvents studied in this work. Therefore, it can penetrate the interfacial film of the reverse micelles and stabilize them by increasing the rigidity of the micellar interface and thus reducing the attractive interaction between the droplets. However, if the CO2 pressure is too high, the solvent strength of the solvents is reduced markedly, and this induces phase separation in the micellar solution. [source] Cathodic Stripping Voltammetry of Uracil.ELECTROANALYSIS, Issue 1 2009Experimental, Theoretical Study Under Conditions of Square-Wave Voltammetry Abstract The electrode mechanism of uracil at a hanging mercury drop electrode (HMDE) is studied under cathodic stripping square-wave voltammetric mode owing to the cathodic dissolution of a sparingly soluble compound formed between the electrode material and uracil. The experimental results can be partly explained in the light of the recent theory for cathodic stripping processes of insoluble salts under conditions of square-wave voltammetry. It is established that the electrode reaction is complicated by attractive interactions between the deposited species of the insoluble compound. To elucidate the electrode mechanism completely a novel theoretical model is developed considering adsorption of the reacting analyte and lateral interactions between species of the insoluble compound. With the help of numerical simulations the effect of interactions is studied in detail, emphasizing the properties of the response that can be used as diagnostic criteria for recognition of the type of interaction forces. Theoretically predicted voltammetric properties agree well with the experimental results enabling clarification of the complex electrode mechanism of uracil at HMDE. [source] Columnar Mesomorphism in Hexacatenar Tetrahedral (2,2,-Bipyridine)zinc Complexes and Homologous Palladium DerivativesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2005Giovanna Barberio Abstract The synthesis and characterisation of novel liquid crystals which display columnar mesomorphism induced upon complexation of a series of nonmesomorphic hexacatenar 4,4,-disubstituted 2,2,-bipyridines (Ln) are reported. The introduction of different metal centres (Zn, Pd) causes the appearance of mesomorphism in all complexes regardless of the geometry around the metal ion. We therefore report the first examples of mesomorphism in tetrahedral zinc derivatives. The nature of the columnar phases is related to the self-assembly of the half-disc shaped [LnMCl2] (M = Zn, Pd) complexes into full disc-shaped supramolecules. The molecular organisation in the mesophase is mainly driven by intermolecular attractive interactions, as shown by the crystal structure of the model compound [LPdCl2]. Preliminary measurements of photoconductivity have been performed on samples of [LnMCl2] complexes doped with C60 to increase absorption. Promising results were obtained. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005) [source] Interaction of the alpha-helical H6 peptide from the pro-apoptotic protein tBid with cardiolipinFEBS JOURNAL, Issue 21 2009Patrice X. Petit BH3 interacting domain death agonist (Bid), a pro-apoptotic member of the Bcl-2 family of proteins, is activated through cleavage by caspase-8. The active C-terminal fragment of Bid (tBid) translocates to the mitochondria where it interacts with cardiolipins at contact sites and induces the release of cytochrome c by a mechanism that is not yet fully understood. It has been shown that the alpha-helices ,H6 and ,H7 (which create the hairpin-forming domain of tBid) mediate the insertion of Bid into mitochondrial membranes and are essential for the cytochrome c -releasing activity. In the present study, we focused on the interaction between the ,H6 and the mitochondrial membrane. By the use of single-cell electropermeabilization associated with flow cytometric analysis of intact cells, we demonstrated that H6 is able to induce cell death when used in the micromolar range. We also studied the interactions of the ,H6 with artificial monolayers. We showed that the presence of negatively charged cardiolipins greatly enhances the insertion of ,H6 into the phospholipid monolayer. The modification of two charged amino acid residues in ,H6 abolished its insertion and also its in vivo effects. Furthermore, the negative values of the excess areas of mixing indicate that attractive interactions between cardiolipins and ,H6 occur in the mixed monolayers. Fluorescence microscopy observations revealed that ,H6 significantly disrupts cardiolipin packing and stabilizes the fluid lipid phase. These results suggest that cardiolipins at the contact sites between the two mitochondrial membranes could mediate the binding of tBid via ,H6. [source] Synthetic Hydrophilic Materials with Tunable Strength and a Range of Hydrophobic Interactions,ADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Olha Hoy Abstract The ability to vary, adjust, and control hydrophobic interactions is crucial in manipulating interactions between biological objects and the surface of synthetic materials in aqueous environment. To this end a grafted polymer layer (multi-component mixed polymer brush) is synthesized that is capable of reversibly exposing nanometer-sized hydrophobic fragments at its hydrophilic surface and of tuning, turning on, and turning off the hydrophobic interactions. The reversible switching occurs in response to changes in the environment and alters the strength and range of attractive interactions between the layer and hydrophobic or amphiphilic probes in water. The grafted layer retains its overall hydrophilicity, while local hydrophobic forces enable the grafted layer to sense and attract the hydrophobic domains of protein molecules dissolved in the aqueous environment. The hydrophobic interactions between the material and a hydrophobic probe are investigated using atomic force microscopy measurements and a long-range attractive and contact-adhesive interaction between the material and the probe is observed, which is controlled by environmental conditions. Switching of the layer exterior is also confirmed via protein adsorption measurements. [source] Activated carbon surface modifications by adsorption of bacteria and their effect on aqueous lead adsorptionJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 12 2001J Rivera-Utrilla Abstract The adsorption of Escherichia coli on different activated carbons has been studied. The activated carbon samples used have been characterized, determining their surface area, pore size distribution, elemental analysis, mineral matter analysis and pH of the point of zero charge. The adsorption capacity of these carbons increased with their hydrophobicity and macropore volume. The number of bacteria adsorbed on the demineralized activated carbon in a solution of pH value equal to the iso-electric point of the carbon was negligible. However, in the presence of cations the proportions of bacterial cells adsorbed were 87.8% (Fe3+), 54.7% (Ca2+) and 24.8% (Mg2+) respectively. This increase in adsorption capacity in the presence of electrolytes has been explained on the basis of both the reduction in electrostatic free energy and the increase in cell surface hydrophobicity due to the metal bound by some compounds of the cell membrane. When the solution pH was intermediate between the pH values of the point of zero charge of the carbon and bacteria the number of bacteria adsorbed increased due to the attractive interactions between the carbon and bacteria. The adsorption of bacteria on activated carbons decreased the porosity and increased the negative charge density of the latter. Depending on the experimental conditions used, the presence of bacteria can enhance the capacity of activated carbons to adsorb lead. © 2001 Society of Chemical Industry [source] Thermogelling behaviors of poly(caprolactone- b -ethylene glycol- b -caprolactone) triblock copolymer in the presence of hyaluronic acidJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 11 2008In Yong Kim Abstract In this article, we studied the effect of hyaluronic acid (HA) on thermogelation of poly(caprolactone- b -ethylene glycol- b -caprolactone) (PCL-PEG-PCL) aqueous solution designed as an injectable system for prevention of postsurgical tissue adhesion. The PCL-PEG-PCL triblock copolymers were simply synthesized by ring-opening polymerization of ,-caprolactone (CL) in the presence of PEG as a polymeric initiator. The synthesized copolymers were confirmed by proton nuclear magnetic resonance (1H-NMR) spectroscopy. Possible interactions between HA and PCL-PEG-PCL triblock copolymers in the blend were evaluated by Fourier-transform infrared spectroscopy (FTIR). The effect of HA on the micellization of PCL-PEG-PCL aqueous solution was investigated by dye solubilization method and electrophoretic lighting scattering (ELS) spectrophotometer. Also, the thermogelling behaviors of the PCL-PEG-PCL triblock copolymers in the presence of HA and their mechanism were investigated by test tube inverting method, 13C-NMR, 1H-NMR, Advanced Rheometic Expansion System (ARES), and differential scanning calorimetry (DSC). The PCL-PEG-PCL/HA blend aqueous solutions undergo the sol-gel-sol transition in response to an increase in temperature (10,60 °C) and the gelation of the PCL-PEG-PCL was rather accelerated by HA. Presumably, this accelerated gelation seems to arise from the attractive interactions between them and the effect of chain confinement in the micelle corona region. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3629,3637, 2008 [source] Grafted Polymer Chains Interacting with Substrates: Computer Simulations and ScalingMACROMOLECULAR THEORY AND SIMULATIONS, Issue 9 2008Radu Descas Abstract We review scaling methods and computer simulations used in the study of the static and dynamic properties of polymer chains tethered to adsorbing surfaces under good solvent conditions. By varying both the grafting density and the monomer/surface interactions a variety of phases can form. In particular, for attractive interactions between the chains and the surface the classical mushroom-brush transition known for repulsive substrates splits up into an overlap transition and a saturation transition which enclose a region of semidilute surface states. At high grafting densities oversaturation effects and a transition to a brush state can occur. We emphasize the role of the critical adsorption parameters for a correct description and understanding of such polymer adsorption phenomena. [source] Interactive functional poly(vinylidene fluoride) membranes with modulated lysozyme affinity: a promising class of new interfaces for contactor crystallizersPOLYMER INTERNATIONAL, Issue 12 2009Annarosa Gugliuzza Abstract BACKGROUND: One of the challenges of current researches in biotechnological fields is the achievement of regular and increasingly smaller protein crystals for genomics and biocatalyst applications. The membrane contactor-based methodology appears to be a time-effective and economically competitive technology for accomplishing this target. RESULTS: A new class of interactive polymeric interfaces enabling the nucleation of very small protein crystals in a short time through controlling attractive interactions is discussed. Specifically, the role of attractive interfacial forces between a model lysozyme solution and modified poly(vinylidene fluoride) membranes is examined. The insertion of amphiphilic motifs in the fluorinated membranes allows quicker agglomeration of protein crystals at the membrane surface reducing significantly the induction time for protein nucleation. The chemical nature of the modifier permits the modulation of the membrane affinity to the lysozyme, involving polar and non-polar attractive interactions and preserving intrinsic structural features, transport properties and the hydrophobic character of the interfaces, according to the basics of membrane crystallization technology. The formation of critical nuclei is observed after 3 h and micro-sized crystals are formed in less than 24 h. CONCLUSION: The experimental evidence suggests these membranes as a promising class of interactive interfaces that may rapidly bring advances in genomics research. Copyright © 2009 Society of Chemical Industry [source] Atom force microscopic characterisation of the interaction forces between bovine serum albumin and cross-linked alkylated chitosan membranes in media of different pHPOLYMER INTERNATIONAL, Issue 12 2002Wen Guang Liu Abstract Butyl, octyl and hexadecyl moieties were introduced into chitosan. The adhesion of bovine serum albumin (BSA) onto glucose aldehyde-crosslinked alkylated chitosan membranes in pH media was investigated by probing the force-displacement curves with BSA-coated Atom force microscope (AFM) tips. The results indicated that, at the isoelectric point (IP), the sample membranes exhibited higher adhesion forces; and deviating from IP ie at pH 2, pH 6, the adhesion forces decreased. The adhesion forces at pH 2 are less than those at pH 6 due to the presence of electrostatic repulsive and attractive interactions, respectively. Measurements of the adhesion force confirmed quantitatively that the introduction of hydrophobic side-chains to chitosan can facilitate protein adsorption; however, longer flexible side-chains can depress protein adsorption to a certain degree. From an analyses of the adhesion forces, it is proposed that protein adsorption can be tuned by adjusting the lengths of the introduced side-alkyl moieties. © 2002 Society of Chemical Industry [source] Effects of additives on surfactant phase behavior relevant to bacteriorhodopsin crystallizationPROTEIN SCIENCE, Issue 12 2006Bryan W. Berger Abstract The interactions leading to crystallization of the integral membrane protein bacteriorhodopsin solubilized in n-octyl-,-D-glucoside were investigated. Osmotic second virial coefficients (B22) were measured by self-interaction chromatography using a wide range of additives and precipitants, including polyethylene glycol (PEG) and heptane-1,2,3-triol (HT). In all cases, attractive protein,detergent complex (PDC) interactions were observed near the surfactant cloud point temperature, and there is a correlation between the surfactant cloud point temperatures and PDC B22 values. Light scattering, isothermal titration calorimetry, and tensiometry reveal that although the underlying reasons for the patterns of interaction may be different for various combinations of precipitants and additives, surfactant phase behavior plays an important role in promoting crystallization. In most cases, solution conditions that led to crystallization fell within a similar range of slightly negative B22 values, suggesting that weakly attractive interactions are important as they are for soluble proteins. However, the sensitivity of the cloud point temperatures and resultant coexistence curves varied significantly as a function of precipitant type, which suggests that different types of forces are involved in driving phase separation depending on the precipitant used. [source] The lines-of-force landscape of interactions between molecules in crystals; cohesive versus tolerant and `collateral damage' contactACTA CRYSTALLOGRAPHICA SECTION B, Issue 3 2010Angelo Gavezzotti A quantitative analysis of relative stabilities in organic crystal structures is possible by means of reliable calculations of interaction energies between pairs of molecules. Such calculations have been performed by the PIXEL method for 1108 non-ionic and 98 ionic organic crystals, yielding total energies and separate Coulombic polarization and dispersive contributions. A classification of molecule,molecule interactions emerges based on pair energy and its first derivative, the interaction force, which is estimated here explicitly along an approximate stretching path. When molecular separation is not at the minimum-energy value, as frequently happens, forces may be attractive or repulsive. This information provides a fine structural fingerprint and may be relevant to the mechanical properties of materials. The calculations show that the first coordination shell includes destabilizing contacts in ,,9% of crystal structures for compounds with highly polar chemical groups (e.g. CN, NO2, SO2). Calculations also show many pair contacts with weakly stabilizing (neutral) energies; such fine modulation is presumably what makes crystal structure prediction so difficult. Ionic organic salts or zwitterions, including small peptides, show a Madelung-mode pairing of opposite ions where the total lattice energy is stabilized from sums of strongly repulsive and strongly attractive interactions. No obvious relationships between atom,atom distances and interaction energies emerge, so analyses of crystal packing in terms of geometrical parameters alone should be conducted with due care. [source] Study of the near-neutral pH-sensitivity of chitosan/gelatin hydrogels by turbidimetry and microcantilever deflectionBIOTECHNOLOGY & BIOENGINEERING, Issue 3 2006Jinshu Mao Abstract The fundamental properties and pH-sensitivity of chitosan/gelating hydrogels were investigated using spectroscopic and microelectro mechanical (MEMS) measurement approaches. Turbidimetric titration revealed that there were electrostatic attractive interactions between tripolyphosphate (TPP), chitosan, and gelatin in the acidic pH range, depending on their degree of ionization. The pH-sensitive swelling behavior of the hydrogels was investigated by monitoring the deflection of hydrogel-coated microcantilevers, which exhibited a sensitive and repeatable response to solution pH. The deflection of the microcantilever increased as the pH decreased, and the response speed of the system exhibited a nearly linear relationship with pH. The effects of the pH and concentration of TPP solution, as well as the ratio of chitosan to gelatin in gel precursor solutions, on the pH sensitivity of the hydrogels were also investigated. It was found that the swelling of the hydrogel is mainly a result of chain relaxation of chitosan,TPP complexes caused by protonation of free amino groups in chitosan, which depends on the crosslinking density set during the formation of the network. An increase in initial crosslink density induced a decrease in swelling and pH sensitivity. It can be concluded from this study that pH-sensitive chitosan gel properties can be tuned by preparatory conditions and inclusion of gelatin. Furthermore, microcantilevers can be used as a platform for gaining increased understanding of environmentally sensitive polymers. © 2006 Wiley Periodicals, Inc. [source] Protein,Protein Interactions in Complex Cosolvent Solutions,CHEMPHYSCHEM, Issue 5 2007Nadeem Javid Abstract The effects of various kosmotropic and chaotropic cosolvents and salts on the intermolecular interaction potential of positively charged lysozyme is evaluated at varying protein concentrations by using synchrotron small-angle X-ray scattering in combination with liquid-state theoretical approaches. The experimentally derived static structure factors S(Q) obtained without and with added cosolvents and salts are analysed with a statistical mechanical model based on the Derjaguin,Landau,Verwey,Overbeek (DLVO) potential, which accounts for repulsive and attractive interactions between the protein molecules. Different cosolvents and salts influence the interactions between protein molecules differently as a result of changes in the hydration level or solvation, in charge screening, specific adsorption of the additives at the protein surface, or increased hydrophobic interactions. Intermolecular interaction effects are significant above protein concentrations of 1 wt,%, and with increasing protein concentration, the repulsive nature of the intermolecular pair potential V(r) increases markedly. Kosmotropic cosolvents like glycerol and sucrose exhibit strong concentration-dependent effects on the interaction potential, leading to an increase of repulsive forces between the protein molecules at low to medium high osmolyte concentrations. Addition of trifluoroethanol exhibits a multiphasic effect on V(r) when changing its concentration. Salts like sodium chloride and potassium sulfate exhibit strong concentration-dependent changes of the interaction potential due to charge screening of the positively charged protein molecules. Guanidinium chloride (GdmCl) at low concentrations exhibits a similar charge-screening effect, resulting in increased attractive interactions between the protein molecules. At higher GdmCl concentrations, V(r) becomes more repulsive in nature due to the presence of high concentrations of Gdm+ ions binding to the protein molecules. Our findings also imply that in calculations of thermodynamic properties of proteins in solution and cosolvent mixtures, activity coefficients may not generally be neglected in the concentration range above 1 wt,% protein. [source] | ||||||||||||||||