The relevance of studying the regulation of protein-ligand interactions is due to the emergence of new views on the role of metabolites and their key importance in vital processes. To study the protein-ligand interaction, the AB0 antigen-antibody blood system and the enzyme-substrate system of dehydrogenases were used as a test system, and ethanol was used as an influencing factor. In experiments performed with A and B blood erythrocyte antigens, natural AB0 system antibodies and monoclonal antibodies under the influence of ethanol performed change of the degree of agglutination and the time to onset of erythrocyte agglutination. It was found that ethanol can regulate the enzyme-substrate interactions of dehydrogenases: lactate dehydrogenase (EC 220.127.116.11), glyceraldehyde phosphate dehydrogenase (EC 18.104.22.168), and α-glycerol phosphate dehydrogenase (EC 22.214.171.124). The increase in the activity of studied enzymes under the influence of ethanol in the whole blood hemolysate was 2.5 - 3 times higher than in the isolated medium (with pure enzyme preparations).
A set of Pitzer parameters was obtained to accurately describe the thermodynamic properties of solutions in the H2O–UO2(NO3)2–Th(NO3)4–HNO3 system at 25°С and represent the thermodynamic properties of liquid phases in the H2O–Th(NO3)4–HNO3 subsystem in the temperature range 25–50°С. Solubility products were calculated for crystal hydrates Th(NO3)4 · 6H2O and UO2(NO3)2 · 3H2O to predict the solubilities of these compounds in those solutions over a wide concentration range.
A set of Pitzer interaction parameters is proposed to describe the thermodynamic properties of the H2O – UO2(NO3)2 – HNO3 solution. This set is reliable at temperatures varying from 15 to 50°C in concentration range of 0 to 40m HNO3 and 0 to 8m UO2(NO3)2. To evaluate these parameters, the following experimental data were used: vapor pressures of the volatile components, dissociation fraction of HNO3, and data on solid-liquid equilibria.
A comprehensive data set of thermodynamic and calorimetric properties of calcium nitrate aqueous solutions, including the heats of dilution, heat capacity, and phase equilibria in a wide temperature and concentration range is thoroughly collected and critically reviewed. A temperature-dependent Pitzer–Simonson–Clegg model is proposed to describe reliably the properties of liquid phase as well as solid–liquid (SLE) and vapor–liquid (VLE) equilibria, including metastable ones, over T = (243.15 to 425.75) K and up to x(Ca(NO3)2) = 0.3. Improved accuracy is obtained as compared to that of earlier models along with incorporating many diverse experimental data types simultaneously.
Liquid – liquid equilibria in the H2O – HNO3 – Eu(NO3)3 – Gd(NO3)3 – tributyl phosphate (TBP) system and in two H2O – HNO3 – Ln(NO3)3 – TBP (Ln = Eu, Gd) subsystems have been investigated at 298.15 K in a wide range of nitric acid and rare earth elements (REEs) concentrations. The total compositions of the extraction systems and the content of REEs and nitric acid in equilibrium phases are presented. Densities of solutions in two subsystems have been measured. The distribution coefficients of REEs and nitric acid and the separation factor of REEs in equilibrium phases have been determined. The obtained experimental data can be further used for thermodynamic modeling of systems that are promising for the extraction separation of REEs.
Saturated vapor pressure of the diluent (toluene, cyclohexane, hexane, heptane) in four binary diluent – di-(2-ethylhexyl)phosphoric (D2EHPA) acid systems was measured by the static method at T = (288.15, 298.15, and 308.15) K in a wide concentration range. Experimental data obtained were correlated with UNIQUAC thermodynamic model taking into account the existence of D2EHPA in the liquid phase in the form of a dimer. Excess molar volumes were determined for binary solutions of D2EHPA with toluene, cyclohexane, heptane in the temperature range of (288.15–308.15) K and hexane at (288.15 and 298.15) K using the vibrating tube densimeter. The Redlich–Kister type polynomial equation was applied to describe the volumetric properties of the solutions.
We formulate a general mean-field theory for a flat electric double layer in ionic liquids and electrolyte solutions with ions possessing static polarizability and a permanent dipole moment on a charged electrode. We establish a new analytical expression for electric double-layer differential capacitance, determining it as an absolute value of the ratio of the local ionic charge density to the local electric field on an electrode surface. We demonstrate that this expression generalizes the analytical expressions previously reported by Kornyshev and Maggs and Podgornik. Using the obtained analytical expression, we explore new features of the differential capacitance behavior with an increase in the static polarizability and permanent dipole moment of cations. We relate these features to the behavior of ionic concentrations on the electrode. In particular, we elucidate the role of the competition between the dielectrophoretic attraction and Coulomb repulsion forces acting on polarizable or polar cations in the electric double layer in the behavior of the differential capacitance. The developed theoretical model and obtained theoretical findings could be relevant for different electrochemical applications, e.g., batteries, supercapacitors, catalysis, electrodeposition, etc.
A new inhibitor of phosphodiesterase (PDE), i.e., nitric oxide (NO) donor, a water soluble DNIC Na[Fe(C7H5N4S)2(NO)2]⋅2.5H2O (1), has been synthesized. The structure of the new complex, its physical-chemical properties in the solid state and in solutions have been studied experimentally (X-ray analysis, IR, UV-Vis, Mossbauer spectroscopy, mass-spectrometry, and amperometry) and theoretically (quantum-chemical modeling by DFT method).
Imidazolone-activated donor–acceptor cyclopropanes undergo alcohol-assisted ring opening under the co-action of p-toluenesulfonic acid. Under the optimized conditions, cyclopropanes and alcohols are coupled in 1,3-fashion with the retention of heterocyclic fragment. Substrates with aromatic donor groups provide the addition products in 75–99% yields as mixtures of two diastereomers.
The interaction of a nitrosyl iron complex with molecular oxygen was studied with Density Functional Theory. On the basis our analysis of the geometric and electronic structure of the complex, three variants of coordination of the oxygen molecule on it were investigated: the attachment of molecular oxygen to the iron center, an insertion of oxygen in between the Fe and NO and the bridging of two nitrosyl ligands. All of the coordination complexes require approximately the same amount of energy input to form. In all of the oxygen-enriched nitrosyl complexes we calculated, the doublet state was energetically below the quartet state. Next, we considered decomposition pathways since the products of all of these oxygen-attaching pathways may then decompose further. The result of this decomposition is either the release of nitrogen monoxide or the release of nitrogen dioxide. For all the three processes, transition and intermediate states were found, as well as the final products. The potential energy surfaces of the most important reactions were plotted. Finally, UV spectra of all the possible products of the oxidation of complex by molecular oxygen were calculated.