scholarly journals Why Do Tetrapropylammonium Chloride and Sulphate Salts Destabilize the Native State of Globular Proteins?

2014 ◽  
Vol 2014 ◽  
pp. 1-4
Author(s):  
Giuseppe Graziano
Keyword(s):  
Aqueous Solutions ◽  
Water Structure ◽  
Globular Proteins ◽  
Volume Effect ◽  
Statistical Thermodynamic ◽  
Water Molecules ◽  
Native State ◽  
Excluded Volume Effect ◽  
Low Charge ◽  
Sulphate Salts

It has recently been shown that aqueous solutions of tetrapropylammonium chloride and sulphate salts destabilize the folded conformation of Trp-peptides (Dempsey et al., 2011). This result is rationalized by the application of a statistical thermodynamic approach (Graziano, 2010). It is shown that the magnitude of the solvent-excluded volume effect, the main contribution for the native state stability, decreases in both aqueous 2 M TPACl solution and aqueous 1 M TPA2SO4solution. This happens because TPA+ions are so large in size and interact so weakly with water molecules, due to their very low charge density, to be able to counteract the electrostrictive effect of chloride and sulphate ions on the water structure, so that the density of their aqueous solutions is smaller or only slightly larger than that of water.

Shedding light on the hydrophobicity puzzle

2016 ◽  
Vol 88 (3) ◽  
pp. 177-188 ◽  
Author(s):  
Giuseppe Graziano
Keyword(s):  
General Theory ◽  
Hydrophobic Hydration ◽  
Volume Effect ◽  
Large Temperature ◽  
Excluded Volume ◽  
Water Molecules ◽  
Main Ingredient ◽  
Excluded Volume Effect ◽  
Translational Entropy ◽  
Nonpolar Molecules

AbstractA general theory of hydrophobic hydration and pairwise hydrophobic interaction has been developed in the last years. The main ingredient is the recognition that: (a) cavity creation (necessary to insert a solute molecule into water) causes a solvent-excluded volume effect that leads to a loss in the translational entropy of water molecules; (b) the merging of two cavities (necessary to form the contact minimum configuration of two nonpolar molecules) causes a decrease in the solvent-excluded volume effect and so an increase in the translational entropy of water molecules. The performance of the theoretical approach is tested by reproducing both the hydration thermodynamics of xenon and the thermodynamics associated with the formation of the contact minimum configuration of two xenon atoms, over a large temperature range.

scholarly journals General Counteraction Exerted by Sugars against Denaturants

Life ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 652
Author(s):  
Serena Cozzolino ◽  
Attila Tortorella ◽  
Pompea Del Vecchio ◽  
Giuseppe Graziano
Keyword(s):  
Pure Water ◽  
Conformational Stability ◽  
Sodium Perchlorate ◽  
Accessible Surface Area ◽  
Volume Effect ◽  
Solvent Accessible Surface Area ◽  
Excluded Volume ◽  
Native State ◽  
Stabilizing Agents ◽  
Excluded Volume Effect

The conformational stability of globular proteins is strongly influenced by the addition to water of different co-solutes. Some of the latter destabilize the native state, while others stabilize it. It is emerging that stabilizing agents are able to counteract the action of destabilizing agents. We have already provided experimental evidence that this counteraction is a general phenomenon and offered a rationalization. In the present work, we show that four different sugars, namely fructose, glucose, sucrose, and trehalose, counteract the effect of urea, tetramethylurea, sodium perchlorate, guanidinium chloride, and guanidinium thiocyanate despite the chemical and structural differences of those destabilizing agents. The rationalization we provide is as follows: (a) the solvent-excluded volume effect, a purely entropic effect, stabilizes the native state, whose solvent-accessible surface area is smaller than the one of denatured conformations; (b) the magnitude of the solvent-excluded volume effect increases markedly in ternary solutions because the experimental density of such solutions is larger than that of pure water.

Thermodynamics of dissolving gaseous argon in different solvents

1998 ◽  
Vol 76 (4) ◽  
pp. 437-444 ◽  
Author(s):  
Giuseppe Graziano
Keyword(s):  
Room Temperature ◽  
Qualitative Difference ◽  
Hydrophobic Hydration ◽  
Volume Effect ◽  
Excluded Volume ◽  
Water Molecules ◽  
Structural Reorganization ◽  
Excluded Volume Effect ◽  
Enthalpy And Entropy Changes ◽  
Enthalpy And Entropy

The solvation of argon in 10 different solvents at room temperature is analysed in terms of the theoretical framework developed by Lee. In order to perform calculations, we used the approach devised by Pierotti and firmly validated by Lee's theory. The fair agreement between the experimental and the calculated values of Δ G. Δ H. , and Δ S. is carefully analysed. It proves that the excluded volume effect, due to cavity creation in the solvent, opposes the solubility process. This effect in water is exaggerated by the small size of the water molecules and is the cause of hydrophobicity. The qualitative difference between water and hydrazine with regard to the solvation enthalpy and entropy changes is rationalized on the basis of the contributions arising from the structural reorganization in the two solvents on solute insertion.Key words: hydrophobic hydration, cavity creation, structural solvent reorganization.

scholarly journals INFLUENCE OF HEXAMETHYLPHOSPHOTRIAMIDE MOLECULES ON WATER STRUCTURE

2017 ◽  
Vol 60 (10) ◽  
pp. 36
Author(s):  
Nikolay I. Zheleznyak
Keyword(s):  
Hydrogen Bonds ◽  
Aqueous Solutions ◽  
Structural Characteristics ◽  
Water Structure ◽  
Hydrophobic Hydration ◽  
Organic Component ◽  
Water Molecules ◽  
Polar Group ◽  
Electrolyte System ◽  
Manometric Method

The volume-manometric method was used to measure the solubility of noble gases: helium, argon, and krypton in mixtures of water with HMPA in the region of small additions of the organic component at temperatures of 283.15; 298.15 and 313.15 K. The maximum on the solubility curves is explained by the competing effect of the hydrophobic and hydrophilic hydration of the corresponding fragments of HMPA molecules. The "bond-breaking" model of water was used in the present work. According to this model the possible deformations of the hydrogen bonds are neglected. It makes possible to calculate the fractions of water molecules participating in any number of hydrogen bonds at the specified temperature. The phenomenological model of the structure of HMPA aqueous solutions is presented. On the base of experimental solubility of gases and the permittivity of solutions, it is possible to calculate the structural characteristics of diluted aqueous solutions. In the frame of the model one can determine the contribution of the effects of hydrophobic hydration to the total energy of interactions in the water-non-electrolyte system and describe the changes in water structure in aqueous solutions. It was found that at x = 0.0035 mole fraction of HMPA, there is an increase in the number of water molecules participating in four hydrogen bonds without changing the average number of hydrogen bonds per water molecule. At x = 0.005 the properties of the system are already largely determined by the influence of the polar group (P = O) of the HMPA molecule. At x = 0.0101 additions of the organic component to water lead to the redistribution of H-bonds and have to the same consequences as the increase in temperature from 298.15 to 313.15 K.Forcitation:Zheleznyak N.I. Influence of hexamethylphosphotriamide molecules on water structure. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 10. P. 36-41

Long-Term Correlations In Diffusive Motion Of Water Molecules And Rare Gas Atoms In Helium And Argon Aqueous Solutions

2015 ◽  
Vol 60 (8) ◽  
pp. 757-763 ◽  
Author(s):  
V.P. Voloshin ◽  
◽  
G.G. Malenkov ◽  
Yu.I. Naberukhin ◽  
◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Rare Gas ◽  
Water Molecules ◽  
Diffusive Motion ◽  
Rare Gas Atoms

Konkurrierende Liganden: Theophyllin als nicht- und stark koordinierender Ligand in Quecksilber(II)-Komplexen / Competing Ligands: Theophylline as Non- and Strongly Coordinating Ligand in Mercury(II) Complexes

2006 ◽  
Vol 61 (6) ◽  
pp. 758-765 ◽  
Author(s):  
Matthias Nolte ◽  
Ingo Pantenburg ◽  
Gerd Meyer
Keyword(s):  
Oxygen Atom ◽  
Water Molecule ◽  
Aqueous Solutions ◽  
Single Crystal ◽  
Coordination Polymers ◽  
Water Molecules ◽  
Slow Evaporation ◽  
Monoclinic Symmetry ◽  
X Ray ◽  
Chloride Ligand

[{Hg(CF3)2}(ThpH)(H2O)](H2O) (1), [{Hg4(Thp)4}(ClO4)4(H2O)8](H2O)4 (2), [{Hg(ThpH)2} (NO3)](NO3) (3) and {Hg(Thp)Cl}(H2O) (4) (ThpH = theophylline, C7H8N4O2) have been synthesized by slow evaporation of aqueous solutions of the mercuric salts Hg(CF3)2, Hg(ClO4)2, Hg(NO3)2, or HgCl2 and theophylline. Their crystal structures were determined on the basis of single crystal X-ray data. The coordination polymers 1 and 2 crystallize with triclinic symmetry, P1̅ (no. 2), with a = 468.8(2), b = 1256.4(5), c = 1445.5(6) pm, α = 67.15(3), β = 89.21(3), γ = 89.40(3)° and a = 833.6(1), b = 1862.7(2), c = 2182.9(2) pm, α = 111.61(1), β = 90.98(1), γ = 95.51(1)°, respectively. 3 and 4 crystallize with monoclinic symmetry, Pc (no. 7), a =1194.1(1), b=1258.8(2), c=735.5(2) pm, β =96.96(2)° and P21/n (no. 14), a=1069.0(2), b =911.6(1), c=1089.9(2) pm and β = 96.87(2)°. In 1 the theophylline molecules are non-coordinating to mercury and leave the Hg(CF3)2 molecule unchanged. Only weak electrostatic attractions to one keto-oxygen atom of theophylline and one water molecule hold this co-crystallisate together. In 2, the theophyllinate anion, Thp−, strongly coordinates with both N(7) and N(9) to HgII forming a large ring with eight Hg atoms that incorporates the water molecules. One sort of nitrate ions in 3 is weakly attached to HgII with the theophylline molecules still bound strongly through N(9). The chloride ligand and the theophyllinate ion seem to have the same strengths as ligands in 4 as they are both attached to HgII with the shortest distances possible

Sign in / Sign up

Export Citation Format

Share Document