Temperature-dependent hydration behavior of aqueous lysine: an approach towards protein binding through dielectric...

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 (ε_j), relaxation time (τ_j), dipole moment (μ_j), correlation factor (g_j), and the number of water molecules rotationally bonded by solute molecules (Z_ib), 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 (ΔH_j), molar entropy (ΔS_j), and molar free energy (ΔF_j) were calculated to provide further insights into the system's characteristics and behavior.Communicated by Ramaswamy H. Sarma.