scholarly journals Water structure changes in oxime-mediated reactivation process of phosphorylated human acetylcholinesterase

2018 ◽  
Vol 38 (3) ◽  
Author(s):  
Irina V. Zueva ◽  
Sofya V. Lushchekina ◽  
Patrick Masson
Keyword(s):  
Ammonium Sulphate ◽  
Water Structure ◽  
Free Water ◽  
Hydrophobic Hydration ◽  
Nucleophilic Attack ◽  
Water Molecules ◽  
Neutral Salt ◽  
Salting Out ◽  
Hi 6 ◽  
Structure Changes

The role of water in oxime-mediated reactivation of phosphylated cholinesterases (ChEs) has been asked with recurrence. To investigate oximate water structure changes in this reaction, reactivation of paraoxon-inhibited human acetylcholinesterase (AChE) was performed by the oxime asoxime (HI-6) at different pH in the presence and absence of lyotropic salts: a neutral salt (NaCl), a strong chaotropic salt (LiSCN) and strong kosmotropic salts (ammonium sulphate and phosphate HPO42−). At the same time, molecular dynamic (MD) simulations of enzyme reactivation under the same conditions were performed over 100 ns. Reactivation kinetics showed that the low concentration of chaotropic salt up to 75 mM increased the percentage of reactivation of diethylphosphorylated AChE whereas kosmotropic salts lead only to a small decrease in reactivation. This indicates that water-breaker salt induces destructuration of water molecules that are electrostricted around oximate ions. Desolvation of oximate favors nucleophilic attack on the phosphorus atom. Effects observed at high salt concentrations (>100 mM) result either from salting-out of the enzyme by kosmotropic salts (phosphate and ammonium sulphate) or denaturing action of chaotropic LiSCN. MDs simulations of diethylphosphorylated hAChE complex with HI-6 over 100 ns were performed in the presence of 100 mM (NH4)2SO4 and 50 mM LiSCN. In the presence of LiSCN, it was found that protein and water have a higher mobility, i.e. water is less organized, compared with the ammonium sulphate system. LiSCN favors protein solvation (hydrophobic hydration) and breakage of elelectrostricted water molecules around of oximate ion. As a result, more free water molecules participated to reaction steps accompanying oxime-mediated dephosphorylation.

Recent advancements in plant aquaphotomics – Towards understanding of “drying without dying” phenomenon and its implications

NIR news ◽  
2019 ◽  
Vol 30 (5-6) ◽  
pp. 22-25 ◽  
Author(s):  
Jelena Muncan ◽  
Shinichiro Kuroki ◽  
Daniela Moyankova ◽  
Hiroyuki Morita ◽  
Stefka Atanassova ◽  
...  
Keyword(s):  
Graduate School ◽  
Biomedical Applications ◽  
Climate Changes ◽  
Near Infrared ◽  
Water Structure ◽  
Free Water ◽  
Food Preservation ◽  
Protective Mechanism ◽  
Water Molecules ◽  
Significant Step

The research team of Kobe University’s Graduate School of Agriculture Science, led by Professor Dr Roumiana Tsenkova and a research group from Agrobioinstitute in Sofia, Bulgaria led by Professor Dr Dimitar Djilianov, recently made a significant step forward in understanding the “drying without dying” phenomenon in resurrection plants – a small group of plant species which are able to survive long periods without water. Using aquaphotomics and near infrared spectroscopy, the entire process of desiccation and subsequent rehydration in one such plant – Haberlea rhodopensis was monitored non-destructively and compared with botanically similar, non-resurrection species Deinostigma eberhardtii. The research found that during drying, resurrection plant performs controlled, organized restructuring of water molecular network in its leaves as a preparation for full desiccation which is characterized by accumulation of water molecular dimers and water molecules with four hydrogen bonds, while free water molecules are drastically diminished. This regulation of water structure in the leaves appears to be the protective mechanism against dehydration-induced damages of the tissues which ensures survival in the absence of water. The discovery that water molecular structure is important for preservation of plant tissues not only opens up new possibilities for bioengineering of crops better adapted to combat climate changes but may also have important implications for food preservation industry, preservation of tissues in medicine and in biomedical applications.

scholarly journals Drugs in ultra-high dilution induce changes in the enthalpy associated with loss of crystallization water in lactose

2021 ◽  
Vol 17 (1) ◽  
pp. 14-14
Author(s):  
Atheni Konar ◽  
Tandra Sarkar ◽  
Nirmal Chandra Sukul ◽  
Anirban Sukul
Keyword(s):  
Solid Medium ◽  
Water Structure ◽  
Free Water ◽  
Water Molecules ◽  
Binding Medium ◽  
High Dilution ◽  
Scanning Calorimetry ◽  
Hydrogen Bond Strength ◽  
Ethanol Medium ◽  
Different Levels

Drugs in ultra-high dilution (UHD) are used in homeopathy. Lactose is used as a binding medium for UHD drugs. FTIR and Raman spectroscopy revealed that although devoid of molecules of the starting substance, different UHD drugs exhibit different amounts of free water molecules and variation in hydrogen bond strength. The aim of the present study was to establish whether specific water structures in UHD could specifically modify the water structure in lactose, particularly the water of crystallization. 3 UHD’s (potencies), 30cH, 200cH and 1000cH, of 2 drugs, Natrum muriaticum and Sulphur were mixed to lactose samples separately. Differential scanning calorimetry (DSC) of the samples was measured. The thermograms of potencies mixed to lactose differed from each other with respect to temperature and enthalpy associated with the removal of water of crystallization from lactose. We believe that the tested UHD modified the water structure in lactose thereby changing the enthalpy for the removal of water of crystallization. Different levels of thermal energy are needed to remove both free water molecules and water of crystallization from lactose. UHD’s also contributed to the change in enthalpy associated with the removal of water of crystallization from lactose. The tested UHD might have modified the number and strength of hydrogen bonds in the crystal structure of lactose. Specific water structures in liquid aqueous ethanol medium are transferable to the solid medium(lactose).

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

Temperature and concentration dependence of equivalent conductivity in Ca(NO3)2-CaI2-H2O system

1980 ◽  
Vol 45 (6) ◽  
pp. 1639-1645 ◽  
Author(s):  
Jindřich Novák ◽  
Ivo Sláma
Keyword(s):  
Linear Function ◽  
Concentration Dependence ◽  
Mole Fraction ◽  
Constant Temperature ◽  
Salt Concentration ◽  
Free Water ◽  
Water Molecules ◽  
Equivalent Conductivity ◽  
Calcium Salts ◽  
Fraction I

The dependence of the equivalent conductivity on the temperature and composition of the Ca(NO3)2-CaI2-H2O system was studied. The ionic fraction [I-]/([I-] + [NO-3]) was changed from 0.1 to 0.5, the mole fraction of calcium salts (assumed in anhydrous form in the presence of free water molecules) was 0.075-0.200. The equivalent conductivity was found to be a linear function of the ionic fraction at constant temperature and salt concentration.

Understanding water structure from Raman spectra of isotopic substitution H2O/D2O up to 573 K

2017 ◽  
Vol 19 (32) ◽  
pp. 21540-21547 ◽  
Author(s):  
Qingcheng Hu ◽  
Haiwen Zhao ◽  
Shunli Ouyang
Keyword(s):  
Hydrogen Bonding ◽  
Raman Spectra ◽  
Water Structure ◽  
Free Water ◽  
Isotopic Substitution ◽  
Structure Model ◽  
Single Donor ◽  
Hydrogen Bonded

The OH/OD stretch band features on Raman spectra of isotopic substitution H2O/D2O at temperatures up to 573 K are correlated with a multi-structure model that water has five dominant hydrogen bonding configurations: tetrahedral, deformed tetrahedral, single donor, single hydrogen bonded water and free water.

Motions of water molecules in dilute aqueous solutions of tertiary butyl alcohol; a neutron scattering study of hydrophobic hydration

1970 ◽  
Vol 319 (1537) ◽  
pp. 189-208 ◽  
Keyword(s):  
Aqueous Solutions ◽  
Water Structure ◽  
Hydrophobic Hydration ◽  
Step Length ◽  
Solute Concentration ◽  
Butyl Alcohol ◽  
Tertiary Butyl ◽  
Self Diffusion ◽  
Dilute Aqueous Solutions ◽  
Neutron Scattering Study

Cold neutron inelastic scattering experiments have been performed on dilute aqueous solutions of (CD 3 ) 3 COH and of solutions of (CH 3 ) 3 COH in D 2 O at 21 °C. From the broadening of the quasi-elastic peak and independently determined self-diffusion coefficients ( D ), diffusive lifetimes ( c ) of H 2 O molecules have been calculated as functions of solute concentration. The product Dc is insensitive to concentration, giving a mean diffusion step length of 0.14 nm. The inelastic portion of the spectrum, reflecting lattice-like hydrogen bonding modes indicates that the solute enhances the water ‘structure’ but that such structure bears no resemblance to ice.

Unified Effect of Hydrophobic Hydration on the Dynamics and the Structure of Water Molecules in Lower Alcohol Aqueous Solutions

2011 ◽  
Vol 80 (4) ◽  
pp. 044604 ◽  
Author(s):  
Masaru Nakada ◽  
Kenji Maruyama ◽  
Osamu Yamamuro ◽  
Tatsuya Kikuchi ◽  
Masakatsu Misawa
Keyword(s):  
Aqueous Solutions ◽  
Hydrophobic Hydration ◽  
Water Molecules ◽  
Structure Of Water ◽  
Lower Alcohol

scholarly journals Synthesis, Single Crystal Structural Investigation, Hirshfeld Surface Analysis, Thermoanalysis and Spectroscopic Study of Two New Cu(II) and Co(II) Transition-Metal Complexes

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 986
Author(s):  
Rim Boubakri ◽  
Mirosław Szybowicz ◽  
Mariola Sadej ◽  
Sarra Soudani ◽  
Frédéric Lefebvre ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Single Crystal ◽  
Organic Ligand ◽  
Free Water ◽  
Pyrimidine Ring ◽  
Water Molecules ◽  
Absorption Bands ◽  
Infrared And Raman Spectroscopy ◽  
Homo And Lumo ◽  
Coordinated Water

Two new complexes, [Cu(dimpyr)2(H2O)2](NO3)2.2H2O (1) and (Hamdimpy)2[CoCl4].H2O (2), with the monodentate ligand 2-amino-6-methylpyrimidin-4-(1H)-one (dimpyr) and the countercation 4-amino-2,6-dimetylpyrimidium (Hamdimpy), respectively, were prepared and characterized by single crystal X-ray diffraction, elemental analysis and IR spectroscopy. In (1), the Cu(II) cation is tetracoordinated, in a square plan fashion, by two nitrogen atoms from the pyrimidine ring of the organic ligand and two oxygen atoms of two coordinated water molecules. In the atomic arrangement, the CuO2N2 square planes are interconnected via the formation of O-H…O hydrogen bonds involving both coordinated and free water molecules and NO3− nitrate anions to form inorganic layers parallel to the (a, b) plane at z = (2n + 1)/4. In (2), the central atom Co(II) is four-coordinated in a distorted tetrahedral fashion by four Cl− ions. The [CoCl4]2− tetrahedra are arranged parallel to the plane (110) at x = (2n + 1)/2 and the organic cations are grafted between them by establishing with them hydrogen bonds of CH…Cl and NH…Cl types. The vibrational absorption bands were identified by infrared and Raman spectroscopy. Intermolecular interactions were investigated via Hirshfeld surfaces and electronic properties such as HOMO and LUMO energies were derived. The two compounds were characterized by thermal analysis to determine their thermal behavior with respect to temperature.

scholarly journals Single and multiple excitations in double-core-hole states of free water molecules

2020 ◽  
Vol 53 (22) ◽  
pp. 224002
Author(s):  
T Marchenko ◽  
S Carniato ◽  
G Goldsztejn ◽  
O Travnikova ◽  
L Journel ◽  
...  
Keyword(s):  
Free Water ◽  
Water Molecules ◽  
Core Hole
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