Refractive Indices and Isentropic Compressibilities of Glycylglycine−FeCl₂ in Aqueous Ethanol Mixtures

Abstract

The density and refractive index studies have been carried out for glycylglycine-FeCl 2 in aqueous ethanol mixtures at four different temperatures in the range T ) (288.15 to 318.15) K. A comparative study of the refractive indices obtained experimentally and those calculated by means of Gladstone-Dale and Lorentz-Lorenz relation has been made. Among them, the Gladstone-Dale equation afforded similar values to those obtained experimentally. Isentropic compressibilities, κ S , and excess molar isentropic compressibilities, K S,m E , were estimated using the Kirkwood model. Using the Redlich-Kister type equations, excess partial molar isentropic compressibilities, K S,i E , were also obtained. The observed negative values of K S,2 E in the water-rich region are due to the structural disorderliness. As infinitely dilute water is hydrogen-bonded to ethanol and glycylglycine, the variation of strength of interaction is not sensed by K S,1 E,∞ .

Effect of 1-Ethyl-3-methylimidazolium Bromide Ionic Liquid on the Volumetric Behavior of Some Aqueous l-Amino Acids Solutions

“…The denaturation of a protein in different aqueous solutions containing salts is an important behavior of biological molecules and has been the subject of extensive investigation. − However, the complex configurational and conformational aspects of protein structure in aqueous solution, make it very difficult to directly interpret various biological processes with salts. In recent years, it is recognized that the physicochemical investigations of aqueous solutions containing amino acids − or small peptides − are of considerable importance and will be helpful in the fundamental understanding of denaturation and other complicated biological processes. Among these technologies, volumetric studies − ,− can provide some unique information in terms of ligand-binding properties, as well as the folding/unfolding character and conformational stability of a globular protein. , …”

Excess and deviation properties of {(glycylglycine+ZnCl2) in aqueous methanol} mixtures

“…From the above studies, it is clear that no earlier reports on {(glycylglycine + ZnCl 2 ) aqueous methanol} mixtures are available which can give valuable information on solute-solvent interactions and hydrogen bonding within the studied system. Hence, in continuation of our earlier works [18][19][20][21][22][23][24], we report in this paper the excess molar volumes (V E ), viscosity deviations (Dg), deviations in isentropic compressibility (Dj S ) and excess molar refractive indices ðDR E m Þ for {(glycylglycine + ZnCl 2 ) in aqueous methanol} mixtures under diverse conditions. …”

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

“…Some salts tend to disrupt protein structures whereas others protect them . Many studies of thermodynamic properties of protein model compounds have been carried out in aqueous alkali metal and alkaline earths halide solutions. − Santosh et al have studied the thermodynamic properties of glycylglycine in aqueous FeCl 2 , MnCl 2 , NiCl 2 , and Mn­(COOCH 3 ) 2 solutions − and found that cation and anion play a significant role in influencing the behavior of glycylglycine. In Venkatesu et al’s study, salt effects of KCl, KBr, and KAc on the peptide backbone unit were investigated by transfer free energies .…”