RESUMEN
Present work reports interaction between water and amino acid lysine for understanding the physicochemical properties that will be useful in the structure formation of protein. The dielectric relaxation of aqueous lysine was systematically investigated over a temperature range spanning from 298.15 K to 278.15 K, encompassing frequencies ranging from 10 MHz to 30 GHz, and across a concentration range of 0.152 M to 0.610 M. Within this study, aqueous lysine revealed the presence of two distinct relaxation modes. The low-frequency relaxation process (l-process) is primarily associated with the relaxation of lysine molecules, whereas the high-frequency relaxation process (h-process) is attributed to water molecules interacting with lysine. Several key dielectric parameters, including static dielectric constant (εj), relaxation time (τj), dipole moment (µj), correlation factor (gj), and the number of water molecules rotationally bonded by solute molecules (Zib), were meticulously determined. These parameters were interpreted in terms of molecular interactions, hydrogen bonding, hydrophobicity, and Lys-Lys binding. Additionally, various thermodynamic parameters such as molar enthalpy (ΔHj), molar entropy (ΔSj), and molar free energy (ΔFj) were calculated to provide further insights into the system's characteristics and behavior.Communicated by Ramaswamy H. Sarma.
RESUMEN
Concentration-dependent dielectric response for non-steroidal anti-inflammatory drugs (NSAIDs): Aceclofenac (ACF) and Diclofenac (DCF) in the aqueous leucine solution have been reported at different concentrations and temperatures (298.15 K to 283.15 K). The time domain reflectometry technique in the frequency region of 1 GHz to 30 GHz was used for the present study. Complex permittivity (ε*), static dielectric constant (ε), dielectric relaxation time (τ), dipole moment (µ) and Kirkwood correlation factor (g) have been calculated and discussed in terms of the molecular interaction of water and the used drugs. To give more insights into the structural dynamics of drug-induced amino acids, the study includes molar enthalpy of activation (ΔH), entropy of activation (ΔS), and free energy of activation (ΔF). The overall study concludes that the drug (DCF) having a potent inhibitor of cyclooxygenase found a higher static dielectric constant (ε0) than that of the drug (ACF) having more carbon (C), hydrogen (H), and oxygen (O) in the chain, which is more efficient in controlling pain.Communicated by Ramaswamy H. Sarma.
RESUMEN
Physical, chemical and microbiological stability of the materials is affected by the rotational and translational mobility of free and hydrated water. The role of water in areas such as protein hydration and enzyme activity, food technology, lyophilization and polymers hydration is, therefore, important and can be well understood in terms of dielectric relaxation spectroscopy. Concentration and temperature-dependent hydrophobicity of amino acid is reflected in their tendencies to appear in appropriate positions in proteins. Therefore, to gain more insights on the temperature and concentration dependence of hydrophobicity and structural properties of amino acid, dielectric relaxation of aqueous alanine have been studied in the temperature region 303.15 K to 278.15 K. Time domain spectroscopy have been used in the frequency range of 10 MHz to 30 GHz and in the concentration range 0.18708 ≤ c/M ≤ 0.74831. Two relaxation processes namely the low-frequency relaxation (l) and the high-frequency relaxation (h) has been detected for the aqueous alanine. Dielectric parameters such as static dielectric constant (εj), relaxation time (τj) dipole moments (û) and correlation factor (g) have been studied to investigate molecular interaction between alanine and water. The number of water molecules irrotationally bond by the solute molecules (Zib) was also determined to examine the hydrophobicity of alanine which was found more hydrophobic towards low temperatures and concentrations. Thermodynamic parameters calculated are also supported well for the hydrophobic behaviour of alanine towards low temperatures and concentrations.Communicated by Ramaswamy H. Sarma.