Glycylglycine In Aqueous Solution Research Articles

Insight into intermolecular interactions and hydration properties of biologically active amino acids in aqueous solutions of cefepime: volumetric, compressibility and viscometric studies

The measurement of density, speed of sound and viscosity of an amino acid and its dipeptide i.e., glycine and glycylglycine in aqueous solution of antibiotic drug cefepime has been carried out at various temperatures. The density and speed of sound data has been used to obtain partial molar volume partial molar expansion coefficient second derivative hydration number (), isentropic compressibility partial molar isentropic compressibility partial molar volume of transfer and partial molar isentropic compressibility of transfer The viscosity data have been used to calculate the viscosity B–coefficients, its temperature derivative dB/dT, viscosity B–coefficient of transfer () and various thermodynamic parameters of activation of viscous flow i.e., and for amino acid/peptide in cefepime solutions. The dependence of these parameters upon concentration and temperature clearly suggests the role of amino acid/peptide and cefepime in solute-solvent interactions. The obtained results have been explained on the basis of competing pattern of interactions between the co-solute and solute in the studied ternary system in order to deduce important information regarding drug-amino acid/peptide interactions.

Thermodynamics of Complex Formation of Ce3+ and La3+ Ions with Glycylglycine in Aqueous Solution

Enthalpy of the complex formation between diglycine (HL±) and Ce3+ or La3+ at 308.15 K and ionic strength of 0.5 mol/L (KNO3) has been determined by means of calorimetry. Thermodynamic parameters of the diglycine complexes formation with Ce3+ and La3+ at different metal to ligand molar ratios have been determined.

Measuring the enthalpies of interaction between glycine, L-cysteine, glycylglycine, and sodium dodecyl sulfate in aqueous solutions

Calorimetric measurements of enthalpies of solution Δsol H m for glycine, L-cysteine, and glycylglycine in aqueous solutions of sodium dodecyl sulfate (SDS) with concentrations of up to 0.05 mol kg–1 are made. Standard enthalpy of solution Δsol H 0 and enthalpy of transfer Δtr H 0 of the dipeptide from water into mixed solvent are calculated. The calculated enthalpy coefficients of paired interactions of amino acids and dipeptide with SDS prove to be positive. Hydrophobic interactions between the biomolecules and SDS are found to have a major impact on the enthalpies of interaction in the three-component systems under study, within the indicated range of concentrations.

Transfer Properties of Glycylglycine from Water to Aqueous NaNO3, NaClO4, and Na2SO4 Solutions

Enthalpies of solution and densities of glycylglycine in aqueous solutions of NaNO3, NaClO4, and Na2SO4 were measured at 298.15 K. Standard transfer enthalpies (ΔtrH0), standard transfer partial molar volume (ΔtrVϕ0), and hydration numbers (Nh) have been determined for glycylglycine. All of the ΔtrH0 values are negative in the three salt solutions. The relative order of ΔtrH0 in the same concentration of 1–1 type salts is NaNO3 > NaClO4. The ΔtrH0 in low concentration of Na2SO4 solutions is between the corresponding values in NaNO3 and NaClO4 solutions. With increasing Na2SO4 concentration, the ΔtrH0 values exceed that in NaNO3 solutions. The ΔtrVϕ0 values are positive and vary in the sequence Na2SO4 > NaNO3 > NaClO4. The results were discussed in terms of various interactions.

Thermodynamics of the formation of complexes of copper(II) ions and glycylglycine in aqueous solutions at 298 K according to calorimetry data

Heat effects of the interaction between glycylglycine and copper(II) nitrate solutions are measured by direct calorimetry at a [metal] : [ligand] ratio of 1 : 5 and at different pH values of the solution. The measurements are made at a temperature of 298.15 K and ionic strengths of 0.25, 0.50, and 0.75. KNO3 is used as a background electrolyte. The thermodynamic characteristics of complex formation by the peptide and copper(II) ions in aqueous solutions are determined. Standard enthalpies of the formation of complex particles in aqueous solutions are calculated.

Thermodynamic characteristics of complex formation by Ni2+ ions and glycylglycine in aqueous solutions of KNO3 at 288–308 K

Heat effects of the interaction between glycylglycine and nickel (II) nitrate solutions are measured by direct calorimetry at different pH values and metal: ligand ratios in the temperature range of 288.15 to 308.15 K. KNO3 is used as the background electrolyte. The heat effects of diluting the nickel nitrate solution in solutions of the background electrolyte are determined in order to make the appropriate corrections. The standard thermodynamic characteristics of complex formation by peptides and nickel (II) ions in aqueous solution are calculated. Standard enthalpies of the formation of complex particles NiPep+, NiPep2, and NiPep3− are determined for the first time.

Effect of temperature on thermodynamic characteristics of the dissociation of glycylglycine in aqueous solutions of electrolytes

Heats of reaction of glycylglycine with nitric acid and potassium hydroxide solutions are determined by two calorimetric procedures at 288.15, 298.15, 308.15 K and an ionic strength of solution of 0.25, 0.50, and 0.75 in the presence of KNO3. Standard thermodynamic characteristics (ΔrH°, ΔrG°, ΔrS°, and ΔpC°) are calculated for the acid-base reactions in aqueous peptide solutions. The effects of the concentration of background electrolyte and temperature on the heats of dissociation of glycylglycine are considered.

Molar volume, compressibility and excess properties of glycylglycine in aqueous NiCl 2 solutions

Volumetric and acoustical parameters are reported for glycylglycine in aqueous NiCl 2 solution at T = (288.15–318.15) K. The apparent molar volumes and isentropic compressibilities were calculated from the experimental data of ultrasonic velocity and density. Together with these, excess isentropic compressibility ( κ S E ), excess free volume ( V f E ), excess intermolecular free length ( L f E ) and deviations of ultrasonic velocity (Δ u) were obtained. The results are interpreted in terms of molecular interactions. The results show that the cation and anion play a significant role in influencing the behavior of glycylglycine in aqueous solutions. These effects were also attributed to the doubly charged behavior of glycylglycine and to the formation of physically bonded ion-pairs between charged groups of glycylglycine and cation and anion of the electrolyte.

Enthalpies of solution of glycylglycine in water–organic solvent media at 298.15 K

The enthalpies of solution of glycylglycine in aqueous solution of 1,4-dioxane, acetone, formamide, N-methylformamide and N,N-dimethylformamide, with the co-solvent content up to 0.4 mole fractions, have been measured calorimetrically at T = 298.15 K. The results obtained were used to calculate the standard enthalpies of solution (Δ sol H°) and transfer (Δ tr H°) of the glycylglycine from water into the mixtures as well as the enthalpy coefficients of pair-wise interaction h xy of the solute with the organic co-solvents in aqueous media. The h xy values were correlated with the properties of organic solvents using the Kamlet–Taft equation. The effect of the structure properties of the mixed solvent on the specified enthalpy characteristics of glycylglycine is discussed.

Determination of glycine and glycyl-glycine in aqueous and alcoholic solutions using a piezoresonance sensor

The potential of a piezoresonance sensor fully immersed in the studied solution is shown for the first time by the example of the determination of glycine and glycyl-glycine in aqueous solutions. Metrological parameters are compared for the determination of glycine by capillary electrophoresis and by using the piezoresonance sensor.

The partial molar heat capacities of glycine and glycylglycine in aqueous solution at elevated temperatures and atp = 10.0 MPa

Apparent molar heat capacities have been determined for aqueous solutions of glycine at temperatures from 352.09 K to 470.63 K and glycylglycine at temperatures from 352.09 K to 423.15 K. Both systems were investigated at a pressure of 10.0 MPa. Measurements were performed with a differential flow calorimeter that is capable of operation at temperatures >723 K and pressures to approximately 40.0 MPa. Partial molar heat capacities at infinite dilution have been calculated from apparent molar values and have been corrected for “relaxation" contributions. The reported partial molar heat capacity values for aqueous glycine and glycylglycine solutions have been modelled using the revised Helgeson, Kirkham, and Flowers semi-empirical equations of state. These models for solutions of glycine and glycylglycine in water have been compared with those previously reported in the literature.

Partial Molar Isothermal and Isentropic Compressibilities of Glycine, Alanine, and Glycylglycine in Aqueous Solution at 25 .degree.C

Partial Molar Isothermal and Isentropic Compressibilities of Glycine, Alanine, and Glycylglycine in Aqueous Solution at 25 .degree.C

Reactions of Cu(II) with glycine and glycylglycine in aqueous solution at high concentrations of sodium chloride

The complex equilibria between the Cu(II) ion and the amino acids glycine and alanine and the peptide glycylglycine are studied in aqueous solution at high concentrations of sodium chloride, where condensation of glycine to peptide molecules has been observed. Comparison of the species distribution at the conditions where this reaction takes place leads to the conclusion that Cu(II) is already complexed by chloride and glycine at very low pH values. The presence of chloride in the detected species, and its influence on their stability are discussed.

Measurement of Free Ammonia Produced by X Irradiation of Glycylglycine in Aqueous Solution

This research was initiated to test the validity of predictions based on Monte Carlo calculations of the effect of ionizing radiation on a simple dipeptide. The mechanism for the formation of ammonia, proposed by Garrison, Sokol, and Bennett-Corniea (Radiat. Res. 53, 376-384, 1973), was reevaluated by measuring the yields under deoxygenated and oxygenated conditions. Although free ammonia was formed under both conditions, the yields were different, depending on the concentrations of solute and molecular oxygen. The reaction probabilities of the specific interactions of free radicals formed in pure water with solute and oxygen are discussed to account for the observed difference. Our results obtained after low-dose-rate X irradiation are compared with those obtained by Garrison et al. after high-dose-rate 60Co gamma irradiation.

Partial reduction of imidazolate bridged binuclear copper(II) complex with glycylglycine in aqueous solution

Etude des proprietes redox des complexes dinucleaires de Cu([(glygly) 2 Cu 2 (Im)] − ), servant de modeles pour le centre actif d'une enzyme

Infrared Spectra and Structures of Copper(II) and Zinc(II) Complexes of Glycylglycine in Aqueous Solution

Abstract The infrared spectra of the Cu(II) and Zn(II) complexes of glycylglycine were observed in D2O at various pD values. Large spectral changes in going from acidic to neutral solution were interpreted in terms of the equilibria among free and complexed forms of glycylglycine. In the Cu(II) complex formed for 3<pD<5 the metal-ligand bonding occurs through the amino nitrogen and peptide oxygen. As pD is increased further, the structure of the Cu(II) complex changes into a form in which the metal-ligand bonding occurs through the amino nitrogen, peptide nitrogen (deprotonated), and carboxyl oxygen. In contrast to the Cu(II) complex, no change of structure is found for the Zn(II) complex. The Zn(II) complex formed for pD>5 is similar to the Cu(II) complex present for 3<pD<5.

Dielectric Behaviour of Glycine and Glycylglycine in Water in the Range of MHz

The dielectric behaviour of glycine and glycylglycine in aqueous solution was examined for low concentrations and in the range of MHz, at 273 to 313 K. Only the solutions of glycylglycine exhibit dielectric absorption in the range 7.05 × 108 to 1.6 × 109Hz. The dielectric absorption was attributed to the relaxation of glycylglycine molecules rotating with one or two molecules of water. The charge separation of the dipolar ion in solution was found to be 5.7 Å, the molecular radius 3 Å and the activation energy for the relaxation process 4 kcal/mole.

Piperazinedione formation from esters of dipeptides containing glycine, alanine, and sarcosine: the kinetics in aqueous solution

Piperazinedione formation from the methyl esters of glycylglycine, glycyl-L-alanine, L-alanylglycine, glycyl-sarcosine, and sarcosylglycine and from the ethyl ester of glycylglycine in aqueous solution, pH 7·3–8·5, and 25·0° was studied. It was found to be a self-catalysed reaction and other amines also served as catalysts. Some concomitant ester hydrolysis occurred. The kinetics were analysed by regression analysis and the data fitted equation (i). Values of khyd′, {ks+kOH[OH+]}, kgb, and kgb′ were obtained. Glycylsarcosine methyl ester d[ester, total]/dt=[ester, free base]{ks+kgb‘[amine, free base]+kOH[OH–]}+[ester, free base]2kgb+[ester, total]khyd’(i) cyclised most rapidly (t½ca. 5 min), by more than an order of magnitude, and this was attributed to the much higher content of cis-isomer. The methyl esters of sarcosylglycine and glycylalanine cyclised considerably faster than the glycylglycine ester; sarcosylglycine methyl ester showed evidence of steric hindrance in its smaller self-catalytic (kgb) rate constant. Alanylglycine methyl ester cyclised the slowest and had a markedly low value of kgb. Saponification rates were similar to those of the esters of N-acylamino-acids. The mechanism of the cyclisation process, together with the effects of N- and C-methyl substituents on the reaction at the ester carbonyl carbon and on the ring opening of the piperazinediones are discussed.

Apparent molal volume of glycine, glycolamide, alanine, lactamide, and glycylglycine in aqueous solution at 25 degrees and high pressures.

Apparent molal volume of glycine, glycolamide, alanine, lactamide, and glycylglycine in aqueous solution at 25 degrees and high pressures.